
    [Powered by DNS]

    ¿ <nobreak@nobreak.com> .
    3rd Edition,  1999 03 26, Revision 3.1.2

    HTML(Divided), HTML(Combined), TXT
    --------------------------------------------------------------------
    ߸   ִٸ ణ ð Ͽ ڿ
    ˷ֽñ ٶϴ. ̰  鿡 ùٸ 
    ϴµ ū  ˴ϴ.    
    'http://www.kr.freebsd.org/doc/PoweredByDNS/'    ,
     ȴٸ Ӱ Ȱϼŵ ϴ.
    --------------------------------------------------------------------

       * Domain Name System 
            o DNS Namespace
            o   Resolving
            o θ 밡 ڼ

       * Name Server 
            o Name Server 
            o BIND(Berkeley Internet Name Daemon) ġ
            o ۺ (Public Domain) û
            o ι (Inverse Domain) û
            o Name Server 
                 + BIND-4 Ʈ  named.boot
                 + BIND-8 Ʈ  named.conf
                 + Forward & Reverse Zone ͺ̽
                      + SOA ڵ (Start Of Authority)
                      + NS(Name Server) ڵ
                      + A(Address) & CNAME(Canonical Name) ڵ
                      + MX(Mail eXchanger) ڵ
                      + PTR(Pointer) ڵ
                      + Ÿ ڵ
                      + Zone ͺ̽ Sample
                      + ȣ ü  Zone ͺ̽ Sample
            o Name Server 

       * Ŭ̾Ʈ(Resolver) 
            o Unix ýۿ Ŭ̾Ʈ 
            o Microsoft Windows ýۿ Ŭ̾Ʈ 

       *   (Domain Parenting & Delegation)
            o θ Zone   
            o   
            o   in-addr.arpa 
            o Classless in-addr.arpa 

       * DNS Sendmail
            o MX(Mail eXchange) ˰
            o MX ڵ带  ʴ ȣƮ
            o MX CNAME 
            o Nonrecursive MX lookup
            o Sendmail Virtual Domain 
                 + m4  sendmail.cf 
                 + Forward-map ̺ ۼ
                 + Reverse-map ̺ ۼ
                 + ̺ ȯ  

       * BIND /
            o BIND ñ׳
            o BIND Syslog ޽
            o BIND Syslog / ޽
            o BIND Statistics
            o BIND Bebugging Output

       * DNS   
            o NSLOOKUP
                 +   ˻
                 + ⺻   
                 +  ó ϱ
                 + Zone Transfer
                 + ʱȭ  '.nslookuprc'
            o DIG
            o DNSWALK

       * Miscellaneous
            o FQDN(Fully Qualified Domain Name)
            o DNS BIND 
            o BIND-4(Traditional) BIND-8(Next Generation) 
            o Public Domain
            o CNAME 뿡 
            o Zone ͺ̽ ۼ 
            o ۷ ڵ (Glue Record)
            o Lame Delegation
            o 'Authoritative answer' 'Non-authoritative answer'
            o Positive & Negative Caching
            o Iterative(Nonrecursive) & Recursive Ӽ
            o RTT(Round Trip Time) Nameserver 
            o ϵī
            o Serial Number 
            o IP   TTL 
            o ̷    (Load Sharing Between Mirrored
              Servers)

       *  

    Domain Name System 

    Domain Name System̶ ̸ IP ּҸ Ͽִ Ŵ л
    ̹ ý̴. ͳݿ Ǵ IP(Internet Protocol),
    ׸ IP  ϴ ݽ  
    210.105.79.103   ǥǴ IP ּҸ νϰ Ǵµ, ̷
    IP ּҴ 忡 ؼϱ  ϱⰡ ư, IP
    ּҸδ   ϱ ٴ  ִ. ͳ
      ARPANET  IP Address ̸ Ͽ
    ϰ ϴ  õǾ,    DNS
    Ŀ Ͽ.

    ARPANET  ȣƮ   ʾұ⿡ NIC(Network
    Information Center)κ  ֱ⸶ ȣƮ 
    (HOSTS.TXT) ޾ /etc/hosts Ͽ Ͽ. ׷
     ͳ Ը ȣƮ  Կ  ο ̸ 
    ü ʿ伺 εǾ, 1983 Paul Mockapetris RFC882,
    RFC883( RFC1034 ü) ο  ü  
     ǥϸ, ũ ӽ̽  , л ͺ̽,
    Email   ־ DNS źϿ.

    DNS Namespace

    ARPANET ߾  ü ϳ Ϸ  ȣƮ
    Ͽ, DNS ̰    Ʈȭ Ͽ [׸
    1]  · Ѵ.

    [Image]
    [׸ 1] Namespace 

    丮     ִµ, Root domain(Ʈ
    ǥõǴ) Top level ο  , Top level  
     ο   /ϴ  Ѵ. ̷
      Ͽ    Ӽ(NS:Name
    Server) л, ȴ.

     YAHOO.COM  COM Ӽ ϵǾ ְ,
    WWW.YAHOO.COM YAHOO.COM Ӽ , ȴ. 
    AV.YAHOO.COM ϱ ؼ YAHOO.COM  ϴ
    Ӽ  ڵ常 ν ϴ. ̷ ӱ
    ϴ ͳ ȣƮ   ȿ ϰ ش.

      Resolving

    [Image]
    [׸ 2]  'WWW.YAHOO.COM'  IP Resolving

      TCP/IP Ŷ θ   . 
    θ  IP ȯ۾(Resolvinb) ϰ Ǵµ, [׸
    2] ̷ Resolving  ش.

      1. Client  'WWW.YAHOO.COM' ϱ  ڽ Local
         Name Server(TCP/IP  ) Ѵ.

      2. Local NS  ڽ ĳ ڷᰡ ִ Ȯ  ߰ߵ
          Root NS(Root NS  ִ) Ǹ .
         ׷ Root NS 'WWW.YAHOO.COM' ڷḦ   Ƿ,
         COM  ϴ NS ϶ 亯 ش.

      3. Local NS ٽ COM NS Ǹ , COM NS ٽ
         YAHOO.COM NS Ϸش. (Ʈ(Ʈ) COM  Root
         NS  Ǳ     Ͼ ʰ
         (2) ٷ YAHOO.COM NS ϶ 亯 ´.)

      4. Local NS YAHOO.COM NS Ѵ. YAHOO.COM NS
         굵ο  ڷḦ ϴ  NS ̹Ƿ,
         'WWW.YAHOO.COM'  IP 204.71.200.74 亯(authoritative
         answer) Ѵ. ( 'WWW.YAHOO.COM'  IP resolving ϸ
         Ź ٸ IP ּҰ Ѿ    ִµ, ̴ Ʈ
         ټ ̷  ǰ,    ش ο
         ټ IP Ͽ ̴. (: "̷  
         ")

      5. , Local NS Client  Ѵ.

    θ 밡 ڼ (: RFC1035 p7, RFC1032 p2)

    'A-Z', 'a-z', '0-9', '-'    ִ. θ ݵ
    ڳ ڷ Ͽ ϸ,  ڿ  ȴ. (ʱ
    [RFC1035] θ ݵ ڷ ϵ Ͽ,
    [RFC1123 p12] ȭǾ 3com.com    Ǿ.)
      /ڿ   , Ʈ иǴ 
    ڿ(Each segment) ְ 63 ܾ(octet)   ֵ
    Ǿ (NIC 12ܾ Ϸ ϱ⸦ ),
    /ҹڴ е ʴ´.

    ٿ, θ ϱ(KRNIC, INTERNIC ) , ݾ
     Ģ  . KRNIC ڷ ϴ θ
     ʴ ݸ ׸Ʈ 63ڱ Ǯ, INTERNIC
    ڷ ϴ  ǰ, ׸Ʈ 22ڷ Ѵ.

     θ  Email ǹǷ RFC822 Ģ
    ؼؾ  ʿ䰡  ˾ƾ Ѵ. , ̴  ο
     Ģ ϹǷ, ũ Ű澵 ʿ ڴ.

    (۵Ǵ Ʈ ǥ ԰ݺ Ȯǰ ϰ Ǿ
     ڷθ  (:411.com) Ѵ.  ǥؿ
    Ǵ   뿡 Ǹ   ٴ ̱⵵
    ϴ)

    Name Server 

    Name Server 

    Ӽ Primary, Secondary, Cache only server еȴ.

    Primary server ش  ϴ  Ӽ̰, Secondary
    server Ư ο  back-up copy ϴ ̴.
    Secondary Primary    ϸ лŰ 
    ϸ, ټ   ִ.   ϱ ؼ
    Primary, Secondary  ʿϰ Ǹ, Secondary Ģ
    ܺ Ʈ ġ   · Primary ٿǾ 
    Ѵ. ,  ϱ ؼ ּ 2(Primary * 1,
    Secondary * n) ̻ Ӽ 䱸ȴ.(δ Primary
    ε  ϰ, Resolver 忡 Primary
    Secondary е ʴ´.)

    Cache only server ο  ͸  ʰ,
    resolving ó ش. ,  簡 ְ  ȸ
    Primary, Secondary Name server  翡 ġѴٰ  ,
    翡 ġ Ʈũ  Local DNS server  ȴ. ̷
      resolving 䱸  ٸ Ʈũ() 
    õϰ ǹǷ ణ ̰  Ǹ,  Ʈũ 
    Ǿ 絵  ͳ  Ұ  ִ. ̷
     翡 Cache only server ϸ ȿ  ذ 
    ִ.

    BIND(Berkeley Internet Name Daemon) ġ

    Name server ϱ ؼ   α׷ ʿϰ
    Ǵµ,  BIND db   ս ǥ  
     μ ͳݿ  θ ȴ. κ Unix
    ýۿ BIND ̹ ġǾ ִ. /usr/sbin 丮
    in.named Ȥ named  Ȯϰ, BIND ̹ ġǾ 
    쿡   ġ BIND  ȮѴ. (BIND
    ̿ )

         $ dig @ns.nobreak.com txt chaos version.bind. | grep VERSION
         VERSION.BIND.           0S CHAOS TXT    "8.1.2"

    'http://www.isc.org/bind.html' BIND ֽŹ Ȯϰ,
    ̰ ų   ɰ  Ǿٸ,
    ׷̵带 ϰ, BIND-4 ġǾ ִٸ, BIND-8
    ̱׷̼Ͽ ο 帧 ϴ°͵  ʰڴ.

    BIND ġ ſ ϴ. 'ftp://ftp.isc.org/isc/bind/src/'
    ֽ  ҽ ޾,  Ǭ   
    Էϴ  ġ ʿ ̴.

         # make clean depend all install

    ׸, ý rc ũƮ  Ͽ ý ý BIND
    ڵ   ֵ Ѵ. (FreeBSD: /etc/rc.conf,
    /etc/rc.network | Solaris: /etc/init.d/inetsvc | Linux
    /etc/rc.d/init.d/named)

    Windows NT, OS/2, MacOS  BIND ϰ Ѵٸ, 
     .

       * http://www.dns.net/dnsrd/docs/exotic.html
       * http://www.isc.org/bind.html

    ۺ (Public Domain) û

    Primary, Secondary Ӽ غǾ, û 
    Ǿٸ,    ("XXX.COM" Internic,
    XXX.CO.KR Krnic)  ûϿ ߱(ӽ̽ ũ)
    ް ȴ.  û  ݾ  Ϲ
    , å, ,  , Ӽ  䱸ȴ. 
    û  ӽ̽ ũϱ  Ӽ  
     ۼѴ.

         2.   Complete Domain Name.......: NOBREAK.COM
         7a.  Primary Server Hostname....: NS.NOBREAK.COM
         7b.  Primary Server Netaddress..: 210.105.79.2
         8a.  Secondary Server Hostname..: NS2.NOBREAK.COM
         8b.  Secondary Server Netaddress: 210.105.79.3

    "NOBREAK.COM" ϵǾٴ ޽ ޾Ҵٸ,   ش
      θ ȮѴ.

         $ nslookup -type=ns nobreak.com
         Server:  ns.nobreak.com
         Address:  0.0.0.0

         nobreak.com     nameserver = ns.nobreak.com
         nobreak.com     nameserver = ns2.nobreak.com
         ns.nobreak.com internet address = 210.105.79.2
         ns2.nobreak.com  internet address = 210.105.79.3

    ش ο  Ӽ û Ͱ  ǥõȴٸ, 
    ٸ  ̴.   ȵǾٸ,   ޽
      ִ.

         *** local.name.server can't find nobreak.com.: Non-existent host/domain

    " NOBREAK.COM ûϴµ   Ϻο ִ
    NS.NOBREAK.COM, NS2.NOBREAK.COM Ҽ ֽϱ?"
    "NS.NOBREAK.COM NOBREAK.COM  û Ϸ  Ӽ
     ־    ʽϱ?" ǹ   ִµ,
        ϱ  Ӽ  
    ο Ǳ  ϴ. (: "۷ ڵ")

    ι (Inverse Domain) û

    ι  IP  ش   ã  ֵ ϴ
    ̴.  ISP(Internet Service Provider) IP Ҵ
      ûѴ.   ι ο  Ӽ
    in-addr.arpa ӽ̽ ϵǾ ִ ȮѴ.

         $ nslookup -type=ns 79.105.210.in-addr.arpa (C Class 210.105.79.x Ҵ ޾ )
         Server:  ns.nobreak.com
         Address:  0.0.0.0

         79.105.210.in-addr.arpa nameserver = ns.nobreak.com
         79.105.210.in-addr.arpa nameserver = ns2.nobreak.com
         ns.nobreak.com  internet address = 210.105.79.2
         ns2.nobreak.com internet address = 210.105.79.3

       ޽ ´ٸ, ι   ȵǾ
    ִ ̹Ƿ, ش ISP ûϿ Ѵ.

         *** ns.nobreak.com can't find 79.105.210.in-addr.arpa.: Non-existent host/domain

    Name Server 

    [׸ 3] 'NOBREAK.COM' ο   Ʈũ  ̴.

    [Image]
    [׸ 3] Ʈũ 

    Ʈũ  3 Ǿ ִ. DNS ϱ , ׸
     ̸   ȣƮ IP ο.  Ӽ
    ns(primary), ns2(secondary) ȣƮ ϰ, IP 1(
    ޾ 쿣 129)  Ȥ ġ, 2 NS, 3 NS2
    ҴѴ.  NOBREAK.COM ռ Internic ûϿ,
    NS.NOBREAK.COM, NS2.NOBREAK.COM Ӽ  ϸ ȴ.

    BIND-4 Ʈ  named.boot

    BIND-4 Ʈ  named.boot BIND õ Ǹ,  
    ʿ ϴ ȯ  ο  Primary/Secondary
     ȴ. Ϲ ý /etc/named.boot ġϸ,
    κ н ŸƮ ũƮ Ʈ  ϸ õ
    BIND ڵ Ѵ. Ʈ ϻ  Ʈ ݵ 1
     Ͽ ϸ ';' ּ ǹѴ.

         directory  /var/named

    'directory' Ʈ  ϵ ġ θ Ÿ. 
    δ Ʈ Ͽ Ÿ ϵ ̽ η ۿѴ. 
    ϵ  θ   ǥؾ ϸ ⼭
    /var/named 丮 ̽ 丮 Ѵ. (κ ý ⺻
    ̽ δ /var/named, /etc/named Ȥ /etc/namedb ̴.)

         cache  . named.root

    cache ڵ  ״ ĳ ƴ϶ Ʈ Ӽ 
    ִ ͺ̽  Ÿ. BIND Ÿ   Ʈ
    Ӽ ϴµ,  Ʈ Ӽ   
    Ͽ ϰ ȴ. '/var/named/named.root'  ̽
    丮 ġŰ ȴ.

    ĳ  Internic ϸ,
    'ftp://ftp.rs.internic.net/domain/named.root'   ִ.
    Ʈ Ӽ     ݾ ٲ , 
    ޿ ѹ Ʈ  ʿ䰡 ִ. ũƮ Cron
      ĳ  Ʈϴ ͵  ̴.

         primary  nobreak.com  zone-nobreak.com

    ش ο  Primary Ӽ  Ѵ. 
    nobreak.com ο    Primary ̸, ͺ̽
     /var/named/zone-nobreak.com  Ÿ.

         secondary  nobreak.com  210.105.79.2  sec-nobreak.com

    ο  Secondary Ӽ Ѵ.  ° ʵ Primary
    Ӽ IP ּ̰,  ° ʵ Primary   zone
      ϸ̴. 210.105.79.2κ nobreak.com 
    ͺ̽ (Zone Transfer)޾ /var/named/sec-nobreak.com
     Ѵ.

    [׸ 3] Ʈũ  Ʈ    ۼ  ִ.

          NS.NOBREAK.COM(Primary NS) /etc/named.boot 
         directory                           /var/named
         cache      .                        named.root
         primary    0.0.127.in-addr.arpa     zone-0.0.127.in-addr.arpa    ; loopback
         primary    79.105.210.in-addr.arpa  zone-79.105.210.in-addr.arpa ; Reverse ZONE
         primary    nobreak.com              zone-nobreak.com             ; Forward ZONE

    '0.0.127.in-addr.arpa' loopback ּ 127.0.0.1  ̴.
    loopback ּҰ  ʴ ý  , 'primary
    0.0.127.in-addr.arpa ...'   Ӽ  ִ. 
       Ҵ C Class IP  210.105.79 
    'nobreak.com'  ̴.

          NS2.NOBREAK.COM(Secondary NS) /etc/named.boot 
         directory                           /var/named
         cache      .                        named.root
         primary    0.0.127.in-addr.arpa     zone-0.0.127.in-addr.arpa
         secondary  79.105.210.in-addr.arpa  210.105.79.2  sec-79.105.210.in-addr.arpa
         secondary  nobreak.com              210.105.79.2  sec-nobreak.com

    Secondary Ӽ ̴. loopback Primary Ƶд.
    Secondary  ̰ ̴.
    (/var/named/zone-0.0.127.in-addr.arpa ־ )

    Secondary ش  Primary Ͽ  ̽
    ۹޾, sec-79.105.210.in-addr.arpa, sec-nobreak.com ,
    Ѵ.

    BIND-8 Ʈ  named.conf

    BIND-4 BIND-8   ۼ ϰ ̰  κ
    ٷ  Ʈ ̴. BIND-8 Ʈ  ⺻  BIND-4
    ,  κ ߰ ȮǾ , ̸ ϰ
     ߰ ս   ֵ   Ǿ.
    ׸  Ʈ ϰ ȥ  named.conf 
    Ǿ.   C   ſ     ִ.
      ϰ   ֵ ۼ ٲ , BIND-4
    Ʈ ϰ ũ ٸ  .  ռ ۼ BIND-4 
    Ʈ  BIND-8 ° ȯ ̴. Ϲ BIND-8 
    Ʈ    ڵ Ȱ, ̳ κ
    Ƿ   ˰ ʹٸ
    'http://www.isc.org/bind8/config.html' ϱ ٶ.

     Primary Ӽ  Ʈ ̴.

          NS.NOBREAK.COM(Primary NS) /etc/named.conf 
         // ̰ ̴ּ. BIND-8 ';' ּ ƴ϶,   ǹѴ.
         options {
                 directory "/var/named";             // Zone  ̽ 丮
                 dump-file "/var/tmp/named_dump.db"; // Dump  Ǵ 
                 statistics-file "/var/tmp/named.stats"; //   Ǵ 
                 pid-file  "/var/run/named.pid";     // μ ID    
         };
         logging {   // ʿ  αϿ  ʴ´.
                 category lame-servers { null; };
                 category cname { null; };
                 category response-checks { null; };
                 category notify { null; };
         };

         zone "." IN {                       // ĳ 
                 type hint;
                 file "named.root";
         };
         zone "0.0.127.in-addr.arpa" IN {    // localhost  Primary  
                 type master;
                 file "zone-0.0.127.in-addr.arpa";
         };
         zone "79.105.210.in-addr.arpa" IN { // Ҵ IP   Reverse Zone
                 type master;
                 file "zone-79.105.210.in-addr.arpa";
         };
         zone "nobreak.com" IN {             //  'NOBREAK.COM'  Forward Zone
                 type master;
                 file "zone-nobreak.com";
         };

    Secondary Ӽ  Ʈ    ۼȴ.

          NS2.NOBREAK.COM(Secondary NS) /etc/named.conf 
         options {
                 directory "/var/named";
         };
         logging {
                 category lame-servers { null; };
                 category cname { null; };
         };

         zone "." IN {
                 type hint;
                 file "named.root";
         };
         zone "0.0.127.in-addr.arpa" IN {    // localhost  Primary  
                 type master;
                 file "zone-0.0.127.in-addr.arpa";
         };
         zone "79.105.210.in-addr.arpa" IN { // Reverse Zone Secondary 
                 type slave;
                 file "sec-79.105.210.in-addr.arpa";
                 masters { 210.105.79.2; };  // Primary NS IP ּ
         };
         zone "nobreak.com" IN {             // 'NOBREAK.COM' Secondary 
                 type slave;
                 file "sec-nobreak.com";
                 masters { 210.105.79.2; };
         };

    Forward & Reverse Zone ͺ̽

    Zone  Forward, Reverse   еȴ. Forward Zone
    ο  IP   ִ ͺ̰̽, Reverse Zone
    IP    ͺ̴̽. ռ named.boot
    Ͽ Ӽ loopback, 79.105.210.in-addr.arpa, nobreak.com
    ο  Primary ϵ Ͽ. 
    zone-0.0.127.in-addr.arpa zone-79.105.210.in-addr.arpa Reverse
    Zone ̰, zone-nobreak.com Forward Zone ̴. Zone
     BIND-4 BIND-8 ۼ ϴ.

     [׸ 3] Ʈũ   Forward Zone 
    zone-nobreak.com ۼϿ .

    SOA ڵ (Start Of Authority)

    Zone  ׻ SOA ڵ Ѵ. SOA ڵ ش ,
    nobreak.com  Ӽ (authoritative) ڷḦ 
     ǹϸ, ڷᰡ  · ,   ֵ Ѵ.

         nobreak.com. IN  SOA  ns.nobreak.com. hostmaster.nobreak.com. (
                               1998122800  ;Serial
                               21600       ;Refresh ( 6 hours)
                               1800        ;Retry   (30 minutes)
                               1209600     ;Expire  (14 days)
                               86400)      ;Minimum ( 1 day)

    1 ش Zone Ͽ  θ . θ 
    Ʈ  .   θ  '@' ǥø Ͽ
    ȴ.

         @            IN  SOA  ns.nobreak.com. hostmaster.nobreak.com. (

    IN(Internet) Ŭ̴. HS, HESIOD, CHAOS  Ŭ
    , Ϲ  Ƿ ׻ IN ȴٰ
    .

    SOA  Primary Ӽ  Email ּҰ .
    'hostmaster.nobreak.com.' Email ּε, Ϲ Email ǥ
    '@' Ʈ ٲپ  ȴ.  Email ο  ߻
    , ̸ ϴ 뵵 ȴ. , Namespace 
      üũϴ κ(lamers  ) ִµ,  κ
     Ͽ 쿡  Email Ͽ ش.

     ȣ ѷ κп Serial, Refresh, Retry, Expire, Minimum
    5 ð() ʵ尡 δ. Minimum  4 ʵ Secondary
    Ӽ ϱ  ̴. ⺻  ''̰, ȣ
    M(Minute), H(Hour), D(Day), W(Week) ٿ 30M, 8H, 2D, 1W 
      ִ.

       * Serial: Serial Secondary Zone  θ  
         ֵ ϱ ̴. Secondary  Serial Primary
         Serial   Zone   ޴´.  Zone
            Serial  ʴ´ٸ, Secondary
         īǸ Ʈ  . Secondary ٸ
         Serial ǹ̰  ׷  Zone  Ǿ
          Serial ϴ   ̴.

       * Serial ǥ ϴ  ں Ϲ 
          YYYYMMDDNN  ǥѴ. YYYYMMDDNN 
         ǥ 4294 ǥ ϴ.

       * Refresh: Primary Zone ͺ̽ θ Secondary
         ˻ϴ ̴ֱ. Ʈũ   Zone 
         ȴٸ, 3H(10800)  Ѵ. Zone Ǵ
          Ϲ 6H(21600) - 12H Ѵ.

       * Retry: Secondary, Primary  ȵ ,  õ
         ð ̴ֱ. Refresh Ⱓ   ǹ̰ ,
         κ  30M(1800) - 1H Ѵ.

       * Expire: Secondary Expire  ð Primary
           ,  ī ڷᰡ  ̻ ȿ
         ʴٰ , ش ο  亯  ʴ´.  
         ʹ  åϴ   ʴ.  1W - 2W(1209600)
         Ѵ.

       * Minimum: Ÿ Ӽ  Zone  ڷḦ   ,
          ڷῡ  ȿⰣ(ĳ ִ ð) Ѵ.
         TTL(Time To Live) õ  ڵ   ⺻
          ȴ. Ư ڵ尡 Ǿ , ̰ ͳݿ
         ĵǾ ƮǴ ֱ   Minimum 
         Ѵ. Ϲ SOA 1D(86400) Ͽ ü
         ڵ忡 ϰ,   Ǵ ڵ常  1H
         - 3H  ߴ  Ѵ. 0 ĳ  
         ǹ̴.

    NS(Name Server) ڵ

    NS ڵ ش ο  Ӽ   Ÿ.

         nobreak.com.   IN  NS      ns.nobreak.com.
                        IN  NS      ns2.nobreak.com.

     ٸ NS Ȱδ, Ŵ ο   ٸ
    Ӽ Ҷ ̴. Namespace   NS ڵ
    ̷ µ, Ŵ   شϴ κ̹Ƿ, ⼭
    ش ο    Ÿٰ ˾Ƶ. "
    " ڼ ٷ.

    A(Address) & CNAME(Canonical Name) ڵ

    A ڵ ο IP οѴ.   . mail power
    A ڵ IP  Ͽ. (mail 'mail.nobreak.com.' ϰ
    ؼȴ.)

         ; Host addresses
         mail.nobreak.com.   IN  A      210.105.79.2
         power               IN  A      210.105.79.103
         ; Aliases
         www                 IN  CNAME  power.nobreak.com.
         ftp                 IN  CNAME  www

    CNAME ڵ ο   ٸ ̸ ϵ Ѵ.
     power.nobreak.com, www.nobreak.com, ftp.nobreak.com 
     IP 210.105.79.103  ȴ. ftp  CNAME CNAME
     ϴ ,  DNS  ڷῡ ٸ ǰ ,
    ̰ ϴ. CNAME ϴ   ڵ带 
    ӹޱ , CNAME   ߰ ڵ带  
     Ѵ. , MX, NS  ڵ忡 CNAME 
     ־ ȵȴ. ݵ Ͽ Ѵ. CNAME ߸
     BIND α׸    ã Ƿ, Ȯ
      ٸ CNAME  ڵ带 ƿ ٸ ڵ ڷ
     ʴ  . õ  ޴ ߿ ƮȰ,
    ս 鿡 CNAME   ʴ 쵵 ִ.
    (: "CNAME 뿡 ")

         ftp                 IN  CNAME  www  ; (X) CNAME ߰ڵ带  
                             IN  MX     mail ;     .

         power               IN  MX 10  mail ; (X) MX CNAME 
         mail                IN  CNAME  ns   ;     ڵ尡   .

    MX(Mail eXchanger) ڵ

    MX ڵ ش ȣƮ   θ Ѵ.  
    Ǿ  , account@nobreak.com    
     'mail.nobreak.com.'  ۵ȴ.  'mail.nobreak.com.'
      ٸ,  켱 'power.nobreak.com' 
    ϰ ȴ. MX Priority_Number   ϸ,
    Priority_Number ڴ  켱 . "MX(Mail
    eXchange) ˰" ڼ ٷ.

         nobreak.com.        IN  MX  10  mail.nobreak.com.
                             IN  MX  20  power.nobreak.com.
         mail.nobreak.com.   IN  A       210.105.79.2
         power.nobreak.com.  IN  A       210.105.79.103

      MX ڵ忡 CNAME    ȵȴ.
    ̷   MTA(Mail Transfer Agent: sendmail)  
    θ ã Ͽ,  ְ  . ̴ ۽ ϴ
    MTA   ̹Ƿ,    ޴ ƴϸ
      ϱ⵵ ƴ. ݵ .

         nobreak.com.        IN  MX  10  mail.nobreak.com.  ; (X) ߸ 
         mail.nobreak.com.   IN  CNAME   power.nobreak.com.
         power.nobreak.com.  IN  A       210.105.79.103

    PTR(Pointer) ڵ

    PTR ڵ IP ּҿ  θ Ͽ ָ, Reverse Zone
    Ͽ ȴ.  IP 210.105.79.2   ̴.

                 2.79.105.210.in-addr.arpa.  IN  PTR  ns.nobreak.com.

    Forward Zone ټ  A(Ȥ CNAME) ڵ带  
    IP   , PTR ڵ ߺ  ʱ , ش
    IP  ǥ θ ϳ Ͽ Ѵ.

    Ÿ ڵ

    Zone ͺ̽ ʿ ڵ   ͸ε
    ,   ڵ Ѵ.  ݵ ʿ
    ,  Ǵ ڵ带 ҰѴ.  ڼ 
    ʿϴٸ RFC1035, RFC1183, RFC2163 .

         power           IN  A      210.105.79.103
                         IN  HINFO  "Sun Sparc Ultra 5"  "Solaris 2.6"
                         IN  TXT    "Nobreak's Primary Server"
                         IN  TXT    "WWW, FTP is now available"
                         IN  RP     hostmaster.nobreak.com.  hostinfo.nobreak.com.
         hostinfo        IN  TXT    "Seung-young Kim, +82-42-864-4440/1"

    HINFO(Host INFOrmation) ڵ   ڿ(CPU , OS
    )  ý  Ÿ. ڿ  ԵǾ
     쿡 ݵ ūǥ Ͽ Ѵ.

    TXT(TeXT) ڵ ؽƮ   øǾ   ִ.
    RP(Responsible Person)   ǥϴµ, Email ּ(@
    Ʈ ġȯ),  (TXT ڵ带  
    ) ´. HINFO   ڵ  
    ġ ƾ Ѵٴ ǰߵ ִ.

    Zone ͺ̽ Sample

    [׸ 3] Ʈũ   Forward Zone 
    zone-nobreak.com   ۼ  ִ.

          'NOBREAK.COM' ο  Forward Zone  /var/named/zone-nobreak.com

         @               IN      SOA     ns.nobreak.com. hostmaster.nobreak.com. (
                                         1998122801  ;Serial
                                         21600       ;Refresh ( 6 hours)
                                         1800        ;Retry   (30 minutes)
                                         1209600     ;Expire  (14 days)
                                         86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nobreak.com.
                         IN      NS      ns2.nobreak.com.
                         IN      MX 10   mail           ;   ȣƮ

         mail            IN      A       210.105.79.2

         ; Hosts Here - This is comments
         router          IN      A       210.105.79.1
         ns              IN      A       210.105.79.2
         ns2             IN      A       210.105.79.3
         power           IN      A       210.105.79.103
                         IN      HINFO   "Sun Sparc Ultra 5"         "Solaris 2.6"
                         IN      TXT     "Nobreak Technologies, Inc."
         www             IN      CNAME   power

    ι   Reverse Zone 
    zone-79.105.210.in-addr.arpa   ۼȴ.

          Reverse Zone  /var/named/zone-79.105.210.in-addr.arpa

         @               IN      SOA     ns.nobreak.com. hostmaster.nobreak.com. (
                                         1998122801  ;Serial
                                         21600       ;Refresh ( 6 hours)
                                         1800        ;Retry   (30 minutes)
                                         1209600     ;Expire  (14 days)
                                         86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nobreak.com.
                         IN      NS      ns2.nobreak.com.
         ; IP-Domain mapping here
         1               IN      PTR     router.nobreak.com.
         2               IN      PTR     ns.nobreak.com.
         3               IN      PTR     ns2.nobreak.com.
         103             IN      PTR     power.nobreak.com.

    loopback ּҸ  Reverse Zone     ۼȴ.
    IP 127.0.0.1 'localhost.' ϴ  ̹Ƿ,  
     Ʈũ ϰ ۼ ̴.

          loopback  Reverse Zone  /var/named/zone-0.0.127.in-addr.arpa

         @               IN      SOA     ns.nobreak.com. hostmaster.nobreak.com. (
                                         1998122801  ;Serial
                                         21600       ;Refresh ( 6 hours)
                                         1800        ;Retry   (30 minutes)
                                         1209600     ;Expire  (14 days)
                                         86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nobreak.com.
                         IN      NS      ns2.nobreak.com.
         ; IP-Domain mapping here
         1               IN      PTR     localhost.

    Zone Ͽ  ǥ ݵ FQDN ǥ  Ѵ.
    BIND Ʈ  ʴ ڿ ȣƮ óϹǷ,
    'ns.nobreak.com' 'ns.nobreak.com.nobreak.com.' ؼѴ.
     'ns.nobreak.com.'  Ʈ  FQDN ǥϰų,
    'ns'  ȣƮ Ͽ Ѵ. Ʈ Դ Ǽ ſ
     ߻ϹǷ, .

    ȣ ü  Zone ͺ̽ Sample

    ȣþü    ټ  ϳ Zone
    ͺ̽   ִ. , ȣ κ 
    Zone Ѵٸ, ȣ  IP ȭ  õ  Zone
    Ǿ ϴ Ȳ  ʱ⸦ ⵵ϰų, ݳ 
    Ҽ ִ ⸦  ̴. ⼭ Ұϴ  ڰ
     ȣ üϼ ϰ Ȱ  , 
    ߰//  ð     ̴.

         * named.boot (BIND-4)
         primary         netbsd.org                      zone-default
         primary         openbsd.org                     zone-default
         ...
         primary         freebsd.org                     zone-freebsd.org     ;  ߰  ʿ 
         ...

         * named.conf (BIND-8)
         zone "netbsd.org"       IN { type master; file "zone-default"; };
         zone "openbsd.org"      IN { type master; file "zone-default"; };
         ...
         zone "freebsd.org"      IN { type master; file "zone-freebsd.org"; };
         ...

         * zone-default
         @               IN      SOA     ns.nobreak.com. hostmaster.nobreak.com. (
                                         1999030601  ;serial
                                         21600       ;Refresh ( 6 hours)
                                         1800        ;Retry   (30 minutes)
                                         1209600     ;Expire  (14 days)
                                         86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nobreak.com.
                         IN      NS      ns2.nobreak.com.
                         IN      A       210.105.79.39
                         IN      MX 10   @
                         IN      MX 20   mqueue.nobreak.com.

         www             IN      CNAME   @
         telnet          IN      CNAME   @
         ftp             IN      CNAME   @
         mail            IN      CNAME   @
         pop             IN      CNAME   @
         news            IN      CNAME   news.nobreak.com.

         * zone-freebsd.org
         $INCLUDE zone-default

         ftp.kr          IN      A       147.46.102.39
         www.kr          IN      CNAME   @

    Name Server 

    Ӽ ϱ   Ǿ.  ϵ
    غǾ Ȯ , Ӽ . Ϸ  
    .

          NS.NOBREAK.COM (BIND-8)
         # ls /etc/named.conf     # BIND-8 Ʈ 
         /etc/named.conf
         # ls /var/named/         # Zone ͺ̽  Ȯ
         named.root
         zone-0.0.127.in-addr.arpa
         zone-79.105.210.in-addr.arpa
         zone-nobreak.com
         # /usr/sbin/named        #    (Solaris: /usr/sbin/in.named)
         # ps ax | grep named     # μ  Ȯ (Solaris: ps -e | grep in.named)
           254  ?  S    0:00 named

          NS2.NOBREAK.COM (BIND-4)
         # ls /etc/named.boot      # BIND-4 Ʈ 
         /etc/named.boot
         # ls /var/named/          # Zone ͺ̽  Ȯ
         named.root
         zone-0.0.127.in-addr.arpa
         # ndc start               # ndc(Name Daemon Control) ġǾ  
         Name Server Started
         # ndc status
           254  ?  S    0:00 named
         # ls /var/named/          # Primary Zone ۿ Ȯ
         named.root
         sec-79.105.210.in-addr.arpa
         sec-nobreak.com
         zone-0.0.127.in-addr.arpa

    ⿡ [׸ 3]  Ʈũ    ٷ,
    ⺻ ʿ κ  Ǿ Ƿ  Ʈũ
        ϸ ȴ.   Ÿ
    Ӽ  Ǹ ν, Namespace   Ǿ
     Ȯ.

         $ nslookup power.nobreak.com ns.nobreak.com   # Primary  Ȯ
         Server:  ns.nobreak.com
         Address:  0.0.0.0

         Name:    power.nobreak.com
         Address:  210.105.79.103

         $ nslookup power.nobreak.com ns2.nobreak.com  # Secondary  Ȯ
         Server:  ns2.nobreak.com
         Address:  210.105.79.3

         Name:    power.nobreak.com
         Address:  210.105.79.103

         $ nslookup power.nobreak.com ns.kornet.ne.kr  # Namespace ũ Ȯ
         Server:  ns.kornet.nm.kr
         Address:  168.126.63.1

         Name:    power.nobreak.com
         Address:  210.105.79.103

     3 ǰ  Ǿٸ, ϴ Ӽ
     ȴٰ ص . Ȯ ϱ ؼ, α
    м  Zone ͺ̽   BIND  ¸
    캸ƾ Ѵ.

    Ŭ̾Ʈ(Resolver) 

    Unix ýۿ Ŭ̾Ʈ 

    Unix ýۻ󿡼 DNS ϱ ؼ /etc/resolv.conf ϰ,
    /etc/nsswitch.conf  պƾ Ѵ. /etc/resolv.conf
     Resolving   Ӽ 3   ִ.
    Ϲ  Primary, Secondary, ISP Ӽ 3  
    Ѵ.

         search nobreak.com       #  Ƚ(Suffix)
         nameserver 210.105.79.2  # ns.nobreak.com
         nameserver 210.105.79.3  # ns2.nobreak.com
         nameserver 168.126.63.1  # ns.kornet.ne.kr (ϴ ISP NS)

    'search nobreak.com' ȣƮ ־  Ƚ 
     Ѵ. ٸ  ȣƮ  ϰų, 
     Ѵٸ, ش       ִ.

         search nobreak.com kr.freebsd.org

    ̷ 쿣 ȣƮ www  www.nobreak.com ȮǾ
    ˻ǰ, ˻   www.kr.freebsd.org ȮǾ ٽ
    ˻ȴ. ߸ ȣƮ ־,   
    ˻ϹǷ,   search Ʈ ϴ  ٶ
    ʴ.

         Ӽ ٸ  
    ִ. ַ Ӽ ĳ   ʰ, ش 
     ﰢ ϱ  δ.

         search nobreak.com

         domain nobreak.com
         nameserver 210.105.79.2
         ...

         domain kornet.ne.kr
         nameserver 168.126.63.1
         ...

    ȣƮ  DNS ȮϿ ˻ϱ ؼ /etc/nsswitch.conf
      'hosts:' 'dns' ߰Ǿ ־ Ѵ. ٷ κ
    OS ⺻ Ǿ , Ȯ ϱ  Ȯ.

         hosts:      files dns

    'files' ȣƮ /etc/hosts Ͽ ˻ Ѵ. ý
    ־ (files, dns) ˻ õѴ.

    Microsoft Windows ýۿ Ŭ̾Ʈ 

    Windows Unix ý /etc/resolv.conf Ͽ شϴ 
    'Ʈũ'   ִ. '' 'Ʈũ' ޴ TCP/IP
      , [׸ 4]  DNS   
    ִ.

    [Image]
    [׸ 4] Windows NT Resolver 

    DNS ϵ PC ȣƮ 'ȣƮ ̸' ִ´. Unix ý
    resolv.conf ϰ Ͽ, '' 'domain', 'DNS 
    ã ' 'nameserver', ' Ƚ ã ' 'search'
    Ʈ شѴ.

      (Domain Parenting & Delegation)

     迭縦   , 迭縦 'www.core.nobreak.com'
       зϿ  ʿ䰡 ִ.  ش
    迭 Ʈũ  , ȿ   ش 
    ش 迭   ִ.

    [Image]
    [׸ 5] Domain Delegation  Namespace 

    [׸ 5] .'FreeBSD.ORG'     
    Ͽ ϰ ְ, 'KR.FreeBSD.ORG'   Ʈ 
    CORE ξƷ ġŴ , 'doc-kr.core.kr.FreeBSD.org'
      Ѵ.    ϳ Ӽ 
       Ʈũ Ը Ҿ    
     ü Ʈũ ε巴 Ѵ.

    θ Zone   

      ݵ ӵǾ ϴ  ƴϴ.   θ
    Zone ͺ̽ Բ ǵ  ִ. ⼭ ȸ系 
    ׷ 'NMS.NOBREAK.COM' зϰ,  Ʒ DNS  
    ̴.

         * zone-nobreak.com (NS.NOBREAK.COM)
         nms                     IN      MX 10   mail.nms
                                 IN      MX 20   mail2.nms
         dns.nms                 IN      A       150.183.110.53
                                 IN      MX 10   mail.nms
                                 IN      MX 20   mail2.nms
         mail.nms                IN      A       150.183.110.10
         mail2.nms               IN      A       150.183.110.11

    'NOBREAK.COM' SOA ڵ尡 ״ Ǳ ,  
     'nms.nobreak.com'  SOA ڵ ʿ䰡 .

      

    'NMS.NOBREAK.COM' Ը Ŀ  лŰ  Ÿ 
     ش  ϰ   NS ڵ带  ش
     ۷ ־ Ѵ.  'NOBREAK.COM' ο
    'NMS' 'ns.nms.nobreak.com'  ̴.

         * zone-nobreak.com (NS.NOBREAK.COM)
         nms                     IN      NS      ns.nms        ; Delegation
                                 IN      NS      ns2.nms
         ns.nms                  IN      A       150.183.110.2 ; Glue Record
         ns2.nms                 IN      A       150.183.110.3

    IP ּҴ A ڵ忡    Ƿ, ݵ ۷ ڵ带
    Ͽ NS Ͽ Ѵ. (: "۷ ڵ")

    Ӽ ns.nms.nobreak.com  ƮϿ   ӹ
    ο  primary  ʿϴ.

         * named.boot (NS.NMS.NOBREAK.COM)
         primary         nms.nobreak.com         zone-nms.nobreak.com

    ׸, Zone ͺ̽ 'zone-nms.nobreak.com'  
    ۼѴ.

         * zone-nms.nobreak.com (NS.NMS.NOBREAK.COM)
         @               IN      SOA     ns.nms.nobreak.com. hostmaster.nms.nobreak.com. (
                                 1999012901  ;Serial
                                 21600       ;Refresh ( 6 hours)
                                 1800        ;Retry   (30 minutes)
                                 1209600     ;Expire  (14 days)
                                 86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.
                         IN      MX 10   mail
                         IN      MX 20   mail2

         ns              IN      A       150.183.110.2
         ns2             IN      A       150.183.110.3
         mail            IN      A       150.183.110.10
         mail2           IN      A       150.183.110.11

         dns             IN      A       150.183.110.53
                         IN      MX 10   mail
                         IN      MX 20   mail2

    Ӽ 'ns2.nms.nobreak.com' Secondary ϱ 
    ƮϿ  ߰Ѵ.

         * named.boot (NS2.NMS.NOBREAK.COM)
         secondary       nms.nobreak.com  150.183.110.2  sec-nms.nobreak.com

     ns, ns.nms, ns2.nms BIND  , ܺ Ӽ
      ȮѴ.

         $ nslookup  -type=NS  nms.nobreak.com  ns.kornet.ne.kr
         nms.nobreak.com nameserver = ns.nms.nobreak.com
         nms.nobreak.com nameserver = ns2.nms.nobreak.com

         $ nslookup  dns.nms.nobreak.com  ns.kornet.ne.kr
         Name:    dns.nms.nobreak.com
         Address:  150.183.110.53

      in-addr.arpa 

    'NOBREAK.COM' B Ŭ 150.183   Ҵ޾Ұ,
    NMS.NOBREAK.COM   150.183.110 Ѵٰ .

         $ nslookup  -type=NS  183.150.in-addr.arpa
         183.150.in-addr.arpa    nameserver = ns.nobreak.com
         183.150.in-addr.arpa    nameserver = ns2.nobreak.com

      Inverse     Ӱ  
    ϰ ̷.  '183.150.in-addr.arpa'
    '110.183.150.in-addr.arpa' ϱ  Zone ̴.

         * zone-183.150.in-addr.arpa (NS.NOBREAK.COM)
         110             IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.

    ׸, 'ns.nms.nobreak.com' 'ns2.nms.nobreak.com' primary,
    secondary  ְ Inverse Zone  ν, ι
       ȴ.

         * named.boot (NS.NMS.NOBREAK.COM)
         primary         110.183.150.in-addr.arpa        zone-110.183.150.in-addr.arpa

         * named.boot (NS2.NMS.NOBREAK.COM)
         secondary       110.183.150.in-addr.arpa        150.183.110.2   sec-110.183.150.in-addr.arpa

         * zone-110.183.150.in-addr.arpa (NS.NMS.NOBREAK.COM)
         @               IN      SOA     ns.nms.nobreak.com. hostmaster.nms.nobreak.com. (
                                 1999012901  ;Serial
                                 21600       ;Refresh ( 6 hours)
                                 1800        ;Retry   (30 minutes)
                                 1209600     ;Expire  (14 days)
                                 86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.

         2               IN      PTR     ns.nms.nobreak.com.
         3               IN      PTR     ns2.nms.nobreak.com.
         10              IN      PTR     mail.nms.nobreak.com.
         11              IN      PTR     mail2.nms.nobreak.com.
         53              IN      PTR     dns.nms.nobreak.com.

    Classless in-addr.arpa  (: RFC2317)

      Ʈ иǴ ׸Ʈ Ȥ (octet) 
    Ǿ ,   ι  ӿ ٸ 
    .  ׸Ʈ  210.105.79.1-128 
    'nobreak.com' 129-256 'nms.nobreak.com' ϴ 쿡
    ι   ġ ʴ.

      ǻ  ̶, ι ο  ġ
    ʰ, ߾ӿ հϴ  ϳ, IP   ISP
    Ŭ (half) Ǵ  ߰  ϰ Ƿ, ̷
     ̿   ذ   Ǿ
    ϰڴ.

    ù° δ 79.105.210.in-addr.arpa  ־
    129-256(B Ҵ) IP  NS ڵ带   NS
    ns.nms.nobreak.com ۷ ش. '79.105.210.in-addr.arpa'
     Zone  ̽' ۼ  .

         * zone-79.105.210.in-addr.arpa (NS.NOBREAK.COM)
         2               IN      PTR     ns.nobreak.com.
         3               IN      PTR     ns2.nobreak.com.
         ...
         129             IN      NS      ns.nms.nobreak.com.   # 129-254 
                         IN      NS      ns2.nms.nobreak.com.
         ...
         254             IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.

    NS ڵ带   ߱ , NS.NMS.NOBREAK.COM Ʈ
    Ͽ IP 129-254     primary  
    ־ Ѵ.  ŷο  ִ.

         * named.boot (NS.NMS.NOBREAK.COM)
         primary  129.79.105.210.in-addr.arpa  zone-129.79.105.210.in-addr.arpa
         ...
         primary  254.79.105.210.in-addr.arpa  zone-254.79.105.210.in-addr.arpa

    ,  Zone  129.79.105.210.in-addr.arpa -
    254.79.105.210.in-addr.arpa     ۼǾ
    Ѵ.

         * zone-129.79.105.210.in-addr.arpa (NS.NMS.NOBREAK.COM)
         @               IN      SOA     ns.nms.nobreak.com. hostmaster.nms.nobreak.com. (
                                 1999012901  ;Serial
                                 21600       ;Refresh ( 6 hours)
                                 1800        ;Retry   (30 minutes)
                                 1209600     ;Expire  (14 days)
                                 86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.
                         IN      PTR     dns.nms.nobreak.com.

         * zone-130.79.105.210.in-addr.arpa (NS.NMS.NOBREAK.COM)
         @               IN      SOA     ns.nms.nobreak.com. hostmaster.nms.nobreak.com. (
                                 1999012901  ;Serial
                                 21600       ;Refresh ( 6 hours)
                                 1800        ;Retry   (30 minutes)
                                 1209600     ;Expire  (14 days)
                                 86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.
                         IN      PTR     dhcp.nms.nobreak.com.

    IPv4 4  еǰ, ̰  4° ݿ 
    Zone ̹Ƿ, ߰ ǰ   .

      ӵ IP ŭ Zone ͺ̽ 䱸Ǳ ,
    ŷο δ   ʴµ,  ̷ Ѱ
     ϰ ҰϿ.

      õ  ִ.

         * zone-79.105.210.in-addr.arpa (NS.NOBREAK.COM)
         2               IN      PTR     ns.nobreak.com.
         3               IN      PTR     ns2.nobreak.com.
         ...
         129             IN      CNAME   129.nms.79.105.210.in-addr.arpa.
         ...
         254             IN      CNAME   254.nms.79.105.210.in-addr.arpa.
         nms             IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.

    Namespace 󿡼 Inverse   'in-addr.arpa' ,
    Ϲ     ̰   .
    ǻ arpa  IP ο ϴ  ̴,
    'nms.79.105.210.in-addr.arpa'    оϴ
     ϰ, ⼭  ̿ Classless in-addr.arpa
    ذϰ ִ.

     '129.79.105.210.in-addr.arpa'
    '129.nms.79.105.210.in-addr.arpa' CNAME ϴµ,
    'nms.79.104.210.in-addr.arpa' primary 'ns.nms.nobreak.com'
    ̹Ƿ, ᱹ   ȴ.

         * named.boot (NS.NMS.NOBREAK.COM)
         primary  nms.79.105.210.in-addr.arpa  zone-nms.79.105.210.in-addr.arpa

         * zone-nms.79.105.210.in-addr.arpa (NS.NMS.NOBREAK.COM)
         @               IN      SOA     ns.nms.nobreak.com. hostmaster.nms.nobreak.com. (
                                         1999012901  ;Serial
                                         21600       ;Refresh ( 6 hours)
                                         1800        ;Retry   (30 minutes)
                                         1209600     ;Expire  (14 days)
                                         86400)      ;Minimum ( 1 day)
                         IN      NS      ns.nms.nobreak.com.
                         IN      NS      ns2.nms.nobreak.com.

         129             IN      PTR     dns.nms.nobreak.com.
         130             IN      PTR     mail.nms.nobreak.com.
         ...
         254             IN      PTR     layla.nms.nobreak.com.

    129-254 PTR ⿡  Ѵ. 79.105.210.in-addr.arpa
    Zone  IP  CNAME ־ ϴ  
     DNS ˰󿡼 ּ  ƴѰ Ѵ.

     ٸ  Ҵ ɰ ϳ Class  Reverse
      ISP ܰ迡 ̷ ,  ISP Class
    θ ó ϴ°찡 κ̿, ش Class ü 
     ϴ 찡 κ̴. ٶ ̷ 쿡
    ӹ  Ÿ  Ҵ IP  Ұ  
    ۷ ־ Ÿ  ذ  . Ӽ Ͽ
    Public IP  ȣƮ(PC Ͽ) Reverse  ȵǾ 
    쿡    źε  , ش ȣƮ
    Reverse Resolving ̰ ϴµ ũ   
    ߱ȴ.

    Classless in-addr.arpa Ӱ  ٸ, ټ C Ŭ
    '210.105.79 - 210.105.81' Ҵ޾Ұ,  81 Ʈũ
     츦 غ. Ѱ , ش ISP
    81.105.210.in-addr.arpa  Ӽ  û ϴ
    ̰,  ̷  ʰ, ⼭ ϴ Ͱ 
    Namespace ũ ش Ʈũ   
    ǵϿ, Ʈũ   ó Ѵ.

    DNS Sendmail

    MX(Mail eXchange) ˰

    MX ڵ ش ȣƮ ŵǴ  ٸ ȣƮ 
    ϵ Ѵ.  ȣƮ    ,
    NOBREAK.COM  ۽ 쿡 Sendmail  ˾ƺ.

         nobreak.com.            IN      MX 10   layla.nobreak.com.
                                 IN      MX 20   marie.nobreak.com.
                                 IN      MX 20   suzi.nobreak.com.

      1. ȣƮ ش ο    ȮѴ.
      2. layla  õѴ.
      3. marie Ȥ suzi  õѴ.
      4. (3) õ  ȣƮ  õѴ.
      5. ü ť ,  Ⱓ ֱ 2-4  ݺѴ.

      ߸ MX   ϳ, layla ٿǾ marie
     ޵Ǿ ,  marie Ϲڽ  ȴٴ
    , ټ MX ڵ   ̴. ̷ Ǹ,
       ȣƮ Ͽ ξ ϸ, ڴ Ź
       ȮϿ Ѵٴ Ľ ٵ, Ϲ
     priority  ȣƮ ť׼ ϵ ϱ 
    ᱹ  ϳ ȣƮ(layla)  ȴ.   marie
    suzi Sendmail   ϵ Ǿ  
    ť׼ Ѵ.

      1. ش (nobreak.com)    ʾƾ Ѵ.
      2.   (Relay) Ͽ Ѵ.

      ʾƾ Ѵٴ  Sendmail w Ŭ(sendmail.cw Ȥ
    sendmail.cf Cw) nobreak.com    ǹϰ, 
    ̶ ŵǴ    ڽ ƴ ,  
        ش ȣƮ  Ѵ. ٷ 
    OS ǵ ⺻ Sendmail ̸ źϵ Ǿ
    ִµ, ̷  ش ȣƮ ť׼  Կ
    .   SMTP  Ÿο    
    IP(Ȥ ) ؼ ̸ ϵ , 
    ť    ǻó ų  IP  ̸
    ϵ Ͽ߸ Ѵ. (: "Allowing controlled SMTP
    relaying in Sendmail 8.9")

    layla  Ҵ  marie ޵Ǵ  ť
    Ǿ 鼭,  Ⱓ(Sendmail.cf 
    Timeout.queuereturn=5d ŭ) ֱ(Sendmail  ,
    Ϲ 30 -q30m)  õȴ.  ݵ layla
    NOBREAK.COM    Ѵ.

         * layla /etc/sendmail.cw (Solaris: /etc/mail/sendmail.cw)
         nobreak.com

    marie suzi 켱 ٴ    ѷ
    ó    ִ. layla ٿǾ  
    marie(Ȥ suzi) ޵ ̰, ش  ť׼ marie
    ٽ MX Ʈ 켱 ԰Ͽ  õ ̴. ᱹ
     suzi ޵ ̰ suzi    ݺѴ.

     ׷? ׷ ִ.  Sendmail  
    ϱ ش  MX Ʈ ľϰ, ڽ 
    (sendmail.cw ϵ) ԵǾ ִ ȮѴ. 
    ԵǾ ִٸ, ĪǴ   (ټ Ī  
    ֱ ) 켱   Ͽ ų (MX 
    ū) ڵ带 MX Ʈ Ѵ.

         nobreak.com.            IN      MX 10   layla.nobreak.com.
                                 IN      MX 20   marie.nobreak.com. ()
                                 IN      MX 20   suzi.nobreak.com.  ()

    ᱹ marie Sendmail ϴ MX Ʈ layla Եǰ,
     ٴ  layla ɶ  ť׵ȴ.

         nobreak.com.            IN      MX 10   layla.nobreak.com.

    ׷  Sendmail ڽ MX Ʈ ã
    ϸ(sendmail.cw 'marie.nobreak.com' ϵǾ  ),
    suzi ʿ  ߻ ̰,  suzi  
    Ȳ̶, ᱹ ѷ  ִ. Sendmail ̷ ־
    Ȳ , ִ  Ƚ (Sendmail.cf
    MaxHopCount=17, ⺻ 25)  Ƿ, ᱹ marie suzi
    MaxHopCount  ɸ ý (postmaster) ۽ڿ
          ̴.

         From: Mail Delivery Subsystem
         To: postmaster@marie.nobreak.com
         Subject: Returned mail: Too many hops 26 (25 max):...

         ----- The following addresses had permanent fatal errors -----

          ----- Transcript of session follows -----
         554 Too many hops 26 (25 max):...
         ===========================================================
         Received: from suzi.nobreak.com by marie.nobreak.com ...
         Received: from marie.nobreak.com by suzi.nobreak.com ...
         ...
         Received: from suzi.nobreak.com by marie.nobreak.com ...
         Received: from marie.nobreak.com by suzi.nobreak.com ...
         ...

      ť ýۿ Ͱ  ߻Ͽ  
    ޽̴.

         nobreak.com.            IN      MX 10   layla.nobreak.com.
                                 IN      MX 20   marie.nobreak.com.

         From: Mail Delivery Subsystem
         To: postmaster@marie.nobreak.com
         Subject: Returned mail: Local configuration error

         ----- The following addresses had permanent fatal errors -----

          ----- Transcript of session follows -----
         553 marie.nobreak.com. config error: mail loops back to me (MX problem?)
         554 ... Local configuration error
         ===========================================================
         ...

    DNS ϵǾ õǴ ȣƮ sendmail.cw  ʾ
     ߻   Ȯ  ٸ, alias  ȣƮ
    sendmail.cw Ͽ ϱ ٶ.

    MX ڵ带  ʴ ȣƮ

    ȣƮ  Ѵٸ MX ڵ带   .

         mailhub         IN      A       210.105.79.107

    ȣƮ mailhub ŵǴ  ٸ ȣƮ  ʿ䰡 
    , ڴ MX ڵ带  ʾҴ.  ̰ 
    ƴ ̷  ͳݻ  MTA mailhub  ۽Ҷ
    ʿ Ʈ  ߻  ִ.

    Sendmail 츦 캸.  Sendmail  Ӽ 
    mailhub lookup(type=any) Ѵ. Authoritative Ȥ
    Non-authoritative Answer A ڵ常 ް ٵ,
    Authoritative Answer  MX ڵ尡   ŷϿ
    ߰   ش IP  õѴ.  MX ڵ尡 
    Non-authoritative Answer  Sendmail  MX ڵ带
     ˻Ѵ.  mailhub MX ڵ带  ʱ  Ͱ
     ʿ Ǹ Ͽ ̴.  Ѵٴ 
         ,     
    ؼ mailhub   Ǵ  ٶϴ.

         mailhub         IN      A       210.105.79.107
                         IN      MX 10   mailhub.nobreak.com.

    mailhub ڽ   ̱ , ڽ MX ߴ.
    ̷,  ϴ  ȣƮ  ڱ ڽ Ѱ
    ̻ MX ڵ带   .

    MX CNAME  ( RFC974 p5)

    MX ڵ带 CNAME ϴ  ſ   ̴.  
    RFC  𿡵  MX ڵ CNAME    
    Ѿ Ȯ      ̷  ݵ 
    ȴٰ   ,   ʿ ߰  
    ߻Ǵ Ʈ   Ⱓ ߸  νĵǾ ԰,
    κ ù    ġ ⸦ Ѵ.

         layla           IN      MX 10   marie.nobreak.com.
         marie           IN      CNAME   suzi.nobreak.com.
         suzi            IN      CNAME   mailhub.nobreak.com.
         mailhub         IN      A       210.105.79.75
                         IN      MX 10   mailhub.nobreak.com.

         * layla  ϱ  lookup 
         1. lookup layla.nobreak.com   -> return marie.nobreak.com
         2. lookup marie.nobreak.com   -> return suzi.nobreak.com
         3. lookup suzi.nobreak.com    -> return mailhub.nobreak.com
         4. lookup mailhub.nobreak.com -> return 210.105.79.75

     ǥ   븶 ݾ  ٸ,
    ǥ BIND  ̸ ߸ ("layla.nobreak.com" IN MX
    points to a CNAME marie.nobreak.com)̶ Syslog  ˷ֽø,
     MTA Sendmail ̸ ( )ϰ ִ.
    ,  MTA ش ý   ϴ 
     Ȱֱ , MX CNAME    ʰ,
       Ѵ.

         layla           IN      MX 10   mailhub.nobreak.com.
         marie           IN      CNAME   mailhub.nobreak.com.
         suzi            IN      CNAME   mailhub.nobreak.com.
         mailhub         IN      A       210.105.79.75
                         IN      MX 10   mailhub.nobreak.com.

    ,  ۽ Sendmail  ּҿ Ե CNAME 
    ȣƮ  Կ . 
    'user@marie.nobreak.com'  ,
    'user@mailhub.nobreak.com'   ۽ŵǸ, ̴ 
      ǥõǴ To:  'user@marie.nobreak.com' ƴ
    'user@mailhub.nobreak.com' Ѵ. ߿  ̷
    ȯ۾ ۽ ̷ٴ ̸, ̴ ȥ ߱ 
    ְ,   Sendmail Virtual Domain   
      ߻ų  ִ.  CNAME  ȣƮ
    ּҷ  ų, CNAME  A ڵ MX ڵ带
    ϴ  .

    Nonrecursive MX lookup

      , mailhub ޵Ǵ  غ. Ϲ
     mx2 ޵Ǹ   , Sendmail MX
    ڵ忡 Nonrecursive ϱ ,   mx1(ݵ A
    ڵ带  Ѵ) ޵ȴ.

                 mailhub         IN      MX 10   mx1.nobreak.com.
                 mx1             IN      MX 10   mx2.nobreak.com.
                                 IN      A       210.105.79.231

     Sendmail MX ڵ带 CNAME Recursiveϰ Ѿưٸ,
        ϰ ǹǷ, Sendmail MX ڵ带
    Ѿư ʴ´.

                 mailhub         IN      MX 10   mx1.nobreak.com.
                 mx1             IN      MX 10   mx2.nobreak.com.
                 mx2             IN      MX 10   mailhub.nobreak.com.   ; Loop

    Sendmail Virtual Domain 

    ϳ ȣƮ   'nobreak.com' 'kr.freebsd.org'
    , Ϲ 'nobreak@nobreak.com' 'nobreak@kr.freebsd.org'
    ڴ . ⿡  κ aliases ̺ 
    Ͱ , ο  ŵǴ  ٸ óϴ 
     ˾ƺ.   Sendmail   ʱ⿡, Sendmail
      ˰ ִٴ  ڳ븸 ٷ絵 ϰڴ.
    Sendmail ͼġ ʴٸ  ϱ  RuleSet, m4, aliases,
    dbm/btree/hash   н ʿ  ִ.

    ϰ ϴ  Sendmail 8.8 ̻󿡼 ϹǷ, 
     ġ  ȮѴ.

         $ telnet localhost smtp
         Trying 127.0.0.1...
         220 kfug2.kr.freebsd.org ESMTP Sendmail 8.9.3/8.9.3

     8.8 ٸ, 'ftp://ftp.sendmail.org/pub/sendmail/'
    ֽŹ ϱ ٶ. Sendmail 8.2 ̻󿡼 'domaintable'
    ǻó    , ⿡ ٷ ʰڴ.

    m4  sendmail.cf 

     'sendmail-VERSION/cf/cf/' ýۿ  mc  
    , Virtual Domain  ʿ 'virtusertable', 'genericstable'
    ǻó ߰Ѵ. ۼ mc  Ϲ   δ.

         * generic-bsd4.4.mc   ۼ freebsd.mc 
         divert(0)dnl
         VERSIONID(`@(#)generic-bsd4.4.mc        8.7 (Berkeley) 5/19/1998')
         OSTYPE(bsd4.4)dnl
         DOMAIN(generic)dnl
         MAILER(local)dnl
         MAILER(smtp)dnl
         FEATURE(virtusertable, btree /etc/domainaliases.db)dnl
         FEATURE(genericstable, btree /etc/useraliases.db)dnl

    'virtusertable' ǻó (in-bound)Ǵ   ڷ
    ϴ RuleSet ϰ, 'genericstable' ǻó ݴ 
      ּҸ ϴ RuleSet Ѵ. DNS Forward
    Zone Reverse Zone ϸ ǰڴ. 'btree' ش
    ̺(domainaliases.db) btree ͺ̽ · 
    Ѵ.  ٸ δ dbm(ndbm ̺귯 ġǾ
    ־ ) hash ִµ, ̺   ȿ dbm(ndbm) >
    btree(Berkeley DB) > hash(db) ̴. ⺻ sendmail
    makemap Berkeley DB ϵ -DNEWDB ÷׷  Ǳ
    , dbm ϱ ؼ ndbm ̺귯 ġϰ,
    Ͻ  -DNDBM ÷׸ ־ Ѵ.

      sendmail.cf Ǿ ϴ Ȳ̶,   
    ǻó ϴ  RuleSet Ͽ sendmail.cf 
    Ͽ . (RuleSet ԵǴ ġ ľϱ  m4
    sendmail.cf Ͽ ϱ ٶ)

         * FEATURE(virtusertable, btree /etc/domainaliases.db)dnl
         # Virtual user table (maps incoming users)
         Kvirtuser btree /etc/domainaliases.db

         # handle virtual users (RuleSet 0 Parse1 Ʒ ġ)
         R$+ < @ $=w . >         $: < $(virtuser $1 @ $2 $@ $1 $: @ $) > $1 < @ $2 . >
         R<@> $+ + $* < @ $* . >
                                 $: < $(virtuser $1 + * @ $3 $@ $1 $: @ $) > $1 + $2 < @
         $3 . >
         R<@> $+ + $* < @ $* . >
                                 $: < $(virtuser $1 @ $3 $@ $1 $: @ $) > $1 + $2 < @ $3 .
          >
         R<@> $+ < @ $+ . >      $: < $(virtuser @ $2 $@ $1 $: @ $) > $1 < @ $2 . >
         R<@> $+                 $: $1
         R< error : $- $+ > $*   $#error $@ $(dequote $1 $) $: $2
         R< $+ > $+ < @ $+ >     $: $>97 $1

         * FEATURE(genericstable, btree /etc/useraliases.db)dnl
         # Generics table (mapping outgoing addresses)
         Kgenerics btree /etc/useraliases.db

         # handle generics database (RuleSet 93 Ʒ ġ)
         R$+ < @ $=G . > $: < $1@$2 > $1 < @ $2 . > @    mark
         R$+ < @ *LOCAL* >       $: < $1@$j > $1 < @ *LOCAL* > @ mark
         R< $+ > $+ < $* > @     $: < $(generics $1 $: $) > $2 < $3 >
         R< > $+ < @ $+ >        $: < $(generics $1 $: $) > $1 < @ $2 >
         R< $* @ $* > $* < $* >  $@ $>3 $1 @ $2                  found qualified
         R< $+ > $* < $* >       $: $>3 $1 @ *LOCAL*             found unqualified
         R< > $*                 $: $1                           not found

    ۼ freebsd.mc    m4(Macro Language Processor)
     sendmail.cf ȯѴ.

         # cd sendmail-VERSION/cf/cf
         # m4 ../m4/cf.m4 freebsd.mc > freebsd.cf
         # cp freebsd.cf /etc/sendmail.cf

    Forward-map ̺ ۼ

    , ش ȣƮ ϴ  Ŭ w(sendmail.cw)
    Ͽ Ѵ.

         * /etc/sendmail.cw 
         nobreak.com
         kr.freebsd.org

    'domainaliases'      Virtual User
    Table ۼѴ.

         * /etc/domainaliases 
         webmaster@nobreak.com           dipper
         moonhunt@nobreak.com            moonhunt@ieee.org
         cjh@nobreak.com                 error:nouser Unknown User
         @nobreak.com                    nobreak
         @kr.freebsd.org                 %1@xfree86.org

    ּ 'webmaster@nobreak.com'   dipper εǰ,
    'moonhunt@nobreak.com' ޵Ǵ  'moonhunt@ieee.org'
     ȴ. 'cjh@nobreak.com' ޵Ǵ  ؼ
    ޽ 'Unknown User' ϸ, ׿ 'nobreak.com' ŵǴ
        nobreak ޵ȴ. ,
    'kr.freebsd.org' ŵǴ   'xfree86.org' 
    ڿ ȴ.   aliases ϰ Ͽ ټ
    ڸ ϴ°  ϴ.

         * /etc/domainaliases 
         announce@kr.freebsd.org         announce.ml
         admin@kr.freebsd.org            admin.ml

         * /etc/aliases 
         announce.ml:            :include:/var/ml/announce.ml
         admin.ml:               nobreak, moonhunt@ieee.org

    Reverse-map ̺ ۼ

    ȣƮ 'kfug2.kr.freebsd.org'϶, ýۿ out-boundǴ
     ⺻ 'user@kfug2.kr.freebsd.org' From ´.
     Reverse-map ̺   ּҸ Ѵ.

         * /etc/useraliases 
         nobreak                 nobreak@nobreak.com
         cjh                     nobreak@kr.freebsd.org

    ̺ ȯ  

    ۼ ̺ makemap  dbm/btree/hash · ȯǾ
    Ѵ. ⼭ btree ϿǷ  Ѵ.

         # makemap btree /etc/domainaliases.db < /etc/domainaliases
         # makemap btree /etc/useraliases.db < /etc/useraliases
         # ls /etc/domainaliases* /etc/useraliases*
         /etc/domainaliases      /etc/useraliases
         /etc/domainaliases.db   /etc/useraliases.db

     Sendmail ϰ  Ȯ.

         # kill -HUP `cat /var/run/sendmail.pid`

         # sendmail -bv webmaster@nobreak.com
         webmaster@nobreak.com... deliverable: mailer local, user dipper

         # sendmail -bv cjh@nobreak.com
         cjh@nobreak.com... Unknown User

         # sendmail -bv anybody@kr.freebsd.org
         anybody@kr.freebsd.org... deliverable: mailer esmtp,
         host xfree86.org., user anybody@xfree86.org

    BIND /

    BIND ñ׳

    BIND      ñ׳ Ѵ. ñ׳ 
     ؼ Ϸ  ϴµ,   /var/named/
    Ȥ /var/tmp/ 丮 ´.

       * HUP: BIND  Ѵ.  Ʈ ̳  ͺ̽
          ,  ñ׳ Ѵ.  ̴ BIND ,
         ϴ Ͱ ٸ, Ʈ ϰ  Zone
         ͺ̽(Serial ) Ʈϰ, ĳ
         Ѵ.
       * INT:  BIND Ʈ ĳ  ͺ̽
         $ORIGIN и ϳ  ϴµ,  
         ͺ̽ named_dump.db Ϸ Ѵ.
       * ILL(BIND-8)/IOT(BIND-4): BIND  named.stats Ϸ
         ߸. Ӽ ,  ʿ   ڷᰡ
         ִ.
       * USR1:   named.run Ϸ Ѵ. BIND 
         ñ׳      ܰ辿 Űµ, 
          ǥϴ   ݾ ϸ, Ϲ
            ڼ  ϵȴ.
       * USR2:   Ѵ.
       * WINCH: BIND ⺻  ֿ ޽ Syslog .
          ñ׳   ۵ϸ, ûǴ  
         Syslog ⵵ Ѵ.

    BIND Syslog ޽

    BIND Syslog  ϻ ˸ ġ  پ
    ޽ . Ӽ Ϲ    
    Syslog ãƳ  ̰ڴ. Syslog
    /etc/syslog.conf   ٸ,  /var/log/messages
    Ȥ /var/adm/messages Ͽ ޽ .

    , BIND  , HUP ñ׳ ޾ ,  
    ϵǴ ϻ ޽̴.

         Jan  1  5:33:39 ns named[288]: starting.  named 8.1.2
         Jan  2 16:57:11 ns named[291]: reloading nameserver
         Feb  5  3:34:31 ns named[289]: named shutting down

    Syslog  ޽  'ð ȣƮ named[PID]: ޽'
     ĸ ϴµ, BIND-4 BIND-8 ׸   Ǵ
    ܾ ޽  ݾ Կ Ѵ.

         Feb  1 11:33:40 ns named[288]: master zone "nobreak.com"
         (IN) loaded (serial 1999012901)

    Zone ͺ̽ ޸𸮿 Ͽ ǹѴ. BIND-4
    'primary zone'̶ ǥϿ, BIND-8 Ѿ鼭 'master
    zone' Ī Ǿ.

    Žð BIND   Ѵ. (BIND-4 Ϻ 
     OS  ϴ BIND  ǻĸ ⺻  ִ.)

         Feb  2 18:57:12 ns named[291]: USAGE 917949432 917837292
         CPU=1558.86u/491.54s CHILDCPU=921.29u/1228.57s

         Feb  2 18:57:12 ns named[291]: NSTATS 917949432 917837292
         Unknown=3 A=95677 NS=3 SOA=275 PTR=563972 MX=11355 TXT=16 AXFR=10 ANY=17840

         Feb  2 18:57:12 ns named[291]: XSTATS 917949432 917837292
         RR=270905 RNXD=92478 RFwdR=133260 RDupR=505 RFail=8882
         RFErr=0 RErr=75 RAXFR=10 RLame=111437 ROpts=0
         SSysQ=24028 SAns=467186 SFwdQ=221971 SDupQ=255265 SErr=5319
         RQ=689151 RIQ=17 RFwdQ=0 RDupQ=224 RTCP=53 SFwdR=133260
         SFail=290 SFErr=0 SNaAns=189120 SNXD=186481

     ޽ ó  2 ڴ ð BIND ۵
    ð ǹѴ. '917949432 - 917837292' ϸ,  
    ð()   ִ. USAGE CPU  Ÿµ,  CPU
    1558ʵ (u) 忡, 491ʵ ý(s) 忡
    Ͽ   ִ. CHILDCPU  ǹε, Ƽ μ
    ý ƴ϶, CHILDCPU 0u/0s  ǥõ ̴. NSTATS
    XSTATS 'BIND Statistics' ڼ ٷ.

                 Feb  5 09:39:05 ns named[26674]: Sent NOTIFY for "nobreak.com IN SOA"
                 (nobreak.com); 1 NS, 1 A

    BIND-8 Ե Dynamic Update  Primary Secondary Zone
    ͺ̽ Ǿ Ʈ϶  . 
    ޽ 'nobreak.com'  Zone ͺ̽ ƮǾ ˸
    ޽ ´ٴ ̴.

         Feb  5 09:36:00 ns named[26674]: ns_forw: query(57.132.119.210.in-addr.arpa)
         No possible A RRs

    Resolver û (ι ) ã    ̴.

         Feb  5 09:35:46 ns named[26674]: Lame server on 'ryu.siyon.com'
         (in 'siyon.com'?): [210.105.79.103].53 'ns.mylover.com'

     'siyon.com' 'ns.mylover.com' ӵǾ, ش
    Ӽ Authority  Ǿ   ̴. ̰ ܺ
    Ʈũ Lame Delegation̹Ƿ Ű  ʾƵ .

    BIND Syslog / ޽

     ޽ ӽ̽  ũ, ߸
    Ӽ   ޽̴.  ޽   Ÿ
    Ӽ  ̰, ǵ 쵵 ,  
     ϵ Ѵ.

         Feb  3 12:53:27 ns named[291]: ns_forw: query(shpark.co.kr)
         contains our address (ns.nobreak.com:210.105.79.2)

     'shpark.co.kr' ns.nobreak.com(ڽ) ӵǾ,
    Authority Ǿ   ̴.  Ʈũ  Lame
    Delegation ޽̴, ش  Ȯϰ,  ġ
    ϵ Ѵ.

         Feb  5 10:09:01 ns named[26674]: "nobreak.com IN NS"
         points to a CNAME (ns.nobreak.com)

         Feb  5 10:09:11 ns named[26674]: "nms.nobreak.com IN MX"
         points to a CNAME (mail.nobreak.com)

         Feb  5 09:57:15 ns named[26674]: power.nobreak.com has CNAME and other data

    CNAME ߸ 뿡  ̴. Ư MX õ 
    ü ƴ  MTA(:sendmail)  ÿ   
    ֱ ,  ã  ð   Ƿ
    .      ,  ޽
    Ÿ.

         nobreak.com.    IN      NS      ns.nobreak.com.   (X) ns CNAME̴.
         ns              IN      CNAME   mild.nobreak.com.

         nms             IN      MX      mail.nobreak.com. (X) mail CNAME ̴.
         mail            IN      CNAME   mhub.nobreak.com.

         power           IN      CNAME   layla.nobreak.com.
                         IN      MX      mhub.nobreak.com. (X)߰ڵ尡   .

    CNAME ڵ  ߰ ڵ嵵   , NS/MX/SOA
    ڵ CNAME    .

         Feb  5 09:24:56 ns2 named-xfer[2502]: record too short from
         [210.105.79.2], zone nobreak.com

    Primary NS xfrnets(BIND-4) Ȥ allow-transfer(BIND-8) ɼ,
    Zone Transfer , ش Zone    ̴. ش
    Ӽ ڿ Ͽ, Zone Transfer ϵ Ͽ
    Ѵ.

    BIND Statistics

    Ӽ Ȱ γ 䱸Ǵ  Ӽ 
    ľϱ Ͽ, ֱ  ڷ 䰡 ʿϴ. ⼭
    Ӽ   м  ˾ƺ Ѵ.  [׸
    6]  timeout(DNS ⺻ UDP ϱ ) 
    ߺ  Ѵ.

    [Image]
    [׸ 6] Ӽ  

    BINDκ    ؼ  
    ILL(BIND-8)/IOT(BIND-4) ñ׳ Ѵ. BIND ñ׳ 
      /var/named/named.stats Ȥ /var/tmp/named.stats
    Ѵ.

         # kill -ILL `cat /var/run/named.pid`
         # ls -al /var/named/named.stats
         -rw-r--r--   1 root     root        19832 Mar  8 04:51 /var/named/named.stats
         # cat /var/named/named.stats
         +++ Statistics Dump +++ (920978301) Tue Mar  9 20:18:21 1999
         208719  time since boot (secs)
         3396    time since reset (secs)
         3       Unknown query types
         205739  A queries
         39      NS queries
         916     SOA queries
         802719  PTR queries
         19192   MX queries
         2       TXT queries
         15      AAAA queries
         129     AXFR queries
         29359   ANY queries

         ++ Name Server Statistics ++
         (Legend)
                 RR      RNXD    RFwdR   RDupR   RFail
                 RFErr   RErr    RAXFR   RLame   ROpts
                 SSysQ   SAns    SFwdQ   SDupQ   SErr
                 RQ      RIQ     RFwdQ   RDupQ   RTCP
                 SFwdR   SFail   SFErr   SNaAns  SNXD
         (Global)
                 447781  164719 227112   869     25991
                 0       245    125      170586  0
                 33963   720395 337570   294284  8122
                 1058113 0      337570   190     0
                 227112  20791  0        228616  298214

         [210.104.247.129]
                 157     0      0        0       10
                 0       0      0        147     0
                 0       36     146      22      0
                 36      0      0        0       0
                 11      0      0        0       13

         .
         .
         .

     BIND 8.1.2   ̴.

         208719  time since boot (secs)
         3396    time since reset (secs)

    BIND   ð  ε(HUP ñ׳
    )   ð ʴ ǥѴ.

         3       Unknown query types

    ˷     Ƚ̴. ̴ ߸ 
    ϰų,   ο ŸԽõ ̴.

         205739  A queries

    A  κ 뿡 䱸ϴ ̸,   䱸ȴ.

         39      NS queries

     BIND Ʈ   Ҷ, NS  Ѵ. ش
     Ʈ  ƴ 쿡 Dig Nslookup  
      û Ѵ.

         916     SOA queries

    SOA  Secondary NS ش Zone ø ȭ ϱ 
    Ѵ.

         802719  PTR queries

    Reverse  䱸ϴ 鿡 ϸ A  Բ  
    ûȴ.

         19192   MX queries

    MX  Sendmail  MTA    ϱ 
    ûѴ.

         2       TXT queries
         15      AAAA queries

    TXT AAAA  Dig Nslookup DNS    ûȴ.

         129     AXFR queries

    AXFR  Secondary Zone Transfer   ûǹǷ,  ġ
    Zone Transfer Ƚ ǹѴ.

         29359   ANY queries

    Any  ٷ Sendmail  ȣƮ A, MX, CNAME 
      Ѵ.

       ȣƮ(Remote Ӽ Stub Resolver)
      Ÿ.    ǥϴ [Global] ʵ Ʒ
     Ȥ õ ȣƮ Ǵµ,   
    ޸𸮸 Һ  Ϲ ߿ġ ʾ, BIND-8 ⺻
    ŵǾ [Global] ʵ常 ǥõȴ. ,  ȣƮ 
    / Ŷ  ڼ  ˷ֱ , Ϲ
    迡 ľ   (Ʈũ  ) ϴµ
     Ǳ⵵ Ѵ.   Ʈ  ɼ ν 
    ȣƮ 踦 ϰ   ִ.

         * named.conf (BIND-8)
         options {
                 host-statistics yes;
         };

    Legend ǥõǴ ڵ  ʵ ǹ̸ Ÿµ, S(Sent)
    ϴ°  ȣƮ ۽ŵ  ǹϰ, R(Received)
     Ѵ.   BIND   ݾ  
    ִ.

         RR(Sent us an answer) 447781
         RQ(Sent us a query) 1058113

    Ʈ ȣƮ  Ӽ (Answer) Ƚ RR̸,
    (Question) Ƚ RQ̴. RR RQ   ƴϹǷ,
    RR RQ ġ 谡 .

         RNXD(Sent us a negative response) 164719
         SNXD(Sent them a negative response) 298214

    RNXD û   ' '  ޾ 
    Ѵ. SNXD ݴ ' '   ̴.

         RFwdR(Sent us a response we had to fwd) 227112
         SFwdR(Forwarded a response to them) 227112
         RFwdQ(Sent us a query we had to forward) 337570
         SFwdQ(Forwarded a query to them) 337570

    Resolver û   Ӽ ӽ̽ ˻Ͽ
     Ʈ Ӽκ   Resolver
    ϴµ, RFwdR Ʈ Ӽκ  (RR)
      ̰, SFwdR    ̴.
    ݴ RFwdQ Resolver (RQ)   û̸, SFwdQ
     Ʈ Ӽ Ǹ  ̴.

         RDupR(Sent us an extra answer) 869
         RDupQ(Sent us a retry) 190
         SDupQ(Sent them a retry) 294284

    Ӽ ٿǾ Timeout ߱ǰų, Ʈũ   ҷ
    ȣƮ Ŷ /ſ  ߻ , ȣƮ
    ߺ(Retry)  û ߻  ִ. RDupR Ʈ ȣƮ
     Ӽ  ߺ ([׸ 6] ó )
    Ƚ̸, RDupQ  Ӽ  ߺ (ش Ǹ ó
    ó  ¿ ŵǴ  ) Ƚ̰, SDupQ 
    Ӽ Ʈ ȣƮ û ߺ  ̴.

         RFail(Sent us a SERVFAIL) 5176
         SFail(Sent them a SERVFAIL) 90

    RFail ȣƮ(Remote) ߸ Zone ͺ̽ , ޸ Ҵ
    , Secondary  Expire     SERVFAIL
     Ƚ Ÿ. SFail  Ӽ  ߼۵
    SERVFAIL ޽̴.

         RFErr(Sent us a FORMERR) 0
         SFErr(Sent them a FORMERR) 0

    RFErr  FORMERR  Ƚ Ÿ. FORMERR  Ʈ
    Ӽ   ִ Ǹ ޾  . SFErr
    ݴ  Ӽ ۽ FORMERR ޽ ̴.
    Ʈũ Ŷۿ  ߻ ʴ     0 ̴.

         RErr(Sent us some other error) 245
         SErr(Sent failed) 8122

    ŵ SERVFAIL  FORMERR ̿  /۽  ޽
    RErr/SErr Եȴ.

         RAXFR(Sent us an AXFR) 125

    AXFR  Secondary Zone Transfer ϱ   . 
    ȣƮ ׸񿡼  ʵ尡 0  쿡 ش ȣƮ 
    Ӽ  ο ؼ Secondary  
    Ѵ.

         RLame(Sent us a lame delegation) 170586

    ӵ   Authority Ǿ  
     0 ƴϴ.  Ư  Ӽ Ǿ 
    Primary Ȥ Secondary   ̴.

         ROpts(Sent us some IP options) 0

    IP ɼ  Ŷ Ͽ , ROpts Ѵ.

         SSysQ(Sent them a sysquery) 33963

     Ӽ ý  Ƚ̴. ý  Ʈ
    Ӽ(Ʈ Ӽ Ͽ)  Ʈ ϱ 
    ȴ.

         RIQ(Sent us an inverse query) 0

    RIQ  Reserve Domain û Ƚ, ٷ BIND PTR
    queries Ǿ  ̻  ʴ´.  RIQ ׻
    0̴.

         RTCP(Sent us a query using TCP) 0

    RTCP TCP   ŵ  Ƚ ǹѴ. κ 
    UDP  /ŵǹǷ   0 ų,  ſ 
    ġ Ѵ.

         SAns(Sent them an answer) 720395
         SNaAns(Sent them a non-autoritative answer) 228616

    SAns û (RQ)   Ƚ ϸ,  ĳ
    ߰ߵǾ 쿡 SNaAns īƮȴ.

    BIND Bebugging Output

    BIND   ڵ Ʈ ͳͽ 
    ȰǹǷ,  ٸ  ϰų BIND  ľϱ 
     ƴ϶,  ̸  Ϸ  ʿ . 
    BIND   ϰ   شȭ ϰ Ѵٸ, 
     м  ̸    ̴.  δ ƴ
      ؼϴ ⺻ ̵ ҰѴ.

         # kill -USR1 `cat /var/run/named.pid` (or 'ndc trace')
         # ping www.openbsd.org.
         # kill -USR2 `cat /var/run/named.pid` (or 'ndc notrace')
         # ls -al /var/named/named.run
         -rw-r--r--  1 root  bin  1153 Mar 10 00:30 named.run

    BIND USR1 ñ׳    Ѵܰ辿 µ,
        ڼ  ǥϿ ش.  
    /var/named/named.run Ȥ /var/tmp/named.run Ϸ Ǹ, ſ
     ϹǷ ʿ  ٰ ǴܵǴ  USR2
    ñ׳ ̿  Ű ٶ. BIND  
    ٹ ߻ϴ     ϵǹǷ,  ϴ
     ߸µ ణ γ ʿ  ִ. BIND ʱȭ
     캸 Ѵٸ 'named -d 1 &'  ý Ŀǵ
    ɼ ־ Ѵ.

         datagram from [210.105.79.6].3442, fd 21, len 33;

    ̰ ȣƮ '210.105.79.6' Ʈ 3442  33 byte UDP
    Ŷ  ũ 6  ŵǾ Ѵ. ⼭
    ϴ  ũͶ  IP ּ(Ŷ listen ϴ) bound
     ڵ鷯 Ѵ.

         req: nlookup(www.openbsd.org) id 28375 type=1 class=1

    û datagram 'www.openbsd.org'  (req)  
    ִ. ü Ŭ IN(class=1)  A(type=1) ڵ
    û̸  йȣ 28375 Ű.

         req: missed 'www.openbsd.org' as '' (cname=0)

    û ο  ˰ִ ڷᰡ (Ӽ ش ο
     Authority   , ĳ ã   )
    Ѵ. 'cname=0' 'www.openbsd.org' CNAME  ʾ
    ϴµ,   ܰ迡 BIND ش  CNAME
    θ ˾Ƴ  ,   0 ƴ 쿡 CNAME
    Ű   ã´.

         forw: forw -> [198.41.0.10].53 ds=23 nsid=19461 id=28375 5ms retry 4sec

    ü lookup Ͽ   ܰ Ǹ
    'J.ROOT-SERVERS.NET(198.41.0.10:53)'  Ѵ.

         datagram from [198.41.0.10].53, fd 21, len 449;
         ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19461
         ;; flags: qr; Ques: 1, Ans: 0, Auth: 12, Addit: 12
         ;; QUESTIONS:
         ;;      www.openbsd.org, type = A, class = IN

         ;; AUTHORITY RECORDS:
         ORG.    518400  IN      NS      A.ROOT-SERVERS.NET.
         ORG.    518400  IN      NS      I.ROOT-SERVERS.NET.
         ORG.    518400  IN      NS      K.GTLD-SERVERS.NET.

         ;; ADDITIONAL RECORDS:
         A.ROOT-SERVERS.NET.     3600000 IN      A       198.41.0.4
         I.ROOT-SERVERS.NET.     3600000 IN      A       192.36.148.17
         K.GTLD-SERVERS.NET.     518400  IN      A       195.8.99.11

    'J.ROOT-SERVERS.NET' û    Դ. ó
     delegation  ۷     µȴ.
     ĳ ȴ.

         resp: nlookup(www.openbsd.org) qtype=1

    ĳ 'www.openbsd.org.' ٽ ã´.

         resp: found 'www.openbsd.org' as 'org' (cname=0)
         resp: forw -> [195.8.99.11].53 ds=23 nsid=19462 id=28375 1ms

    Ϻ  ƴ, ORG   ߰Ͽ ,
    'K.GTLD-SERVERS.NET(195.8.99.11)' Ǹ  Ѵ.

         datagram from [195.8.99.11].53, fd 21, len 219;
         ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19462
         ;; flags: qr rd; Ques: 1, Ans: 0, Auth: 5, Addit: 3
         ;; QUESTIONS:
         ;;      www.openbsd.org, type = A, class = IN

         ;; AUTHORITY RECORDS:
         OPENBSD.org.    172800  IN      NS      ZEUS.THEOS.COM.
         OPENBSD.org.    172800  IN      NS      CVS.OPENBSD.org.
         OPENBSD.org.    172800  IN      NS      NS.SIGMASOFT.COM.

         ;; ADDITIONAL RECORDS:
         ZEUS.THEOS.COM.         172800  IN      A       199.185.137.1
         CVS.OPENBSD.org.        172800  IN      A       199.185.137.3
         NS.SIGMASOFT.COM.       172800  IN      A       209.249.129.35

    'K.GTLD-SERVERS.NET'κ   ۷ 
    ƿԴ.

         resp: nlookup(www.openbsd.org) qtype=1
         resp: found 'www.openbsd.org' as 'openbsd.org' (cname=0)

    ĳ 'www.openbsd.org.' ã  , 'openbsd.org.' 
     ߰ߴ.

         resp: forw -> [199.185.137.3].53 ds=23 nsid=19467 id=28375 22ms
         datagram from [199.185.137.3].53, fd 21, len 272;

    'CVS.OPENBSD.ORG(199.185.137.3)' Ǹ  , 
    (A) Ͽ. (  1   ǥõǱ
    ,     쿡    
    Ͽ߸ Ѵ)

         send_msg -> [210.105.79.6].3442 (UDP 21) id=28375

     ˻  Ŭ̾Ʈ ν, 28375 
     ó  Ǿ.

    DNS   

    NSLOOKUP

    Ӽ ϰ ϴµ ־  ߰ϰ ذϱ 
    Resolver  Ӽ غ ʿ䰡 ִ. κ
    ýۿ ⺻ ġǾ ִ nslookup dig Բ  θ
    Ǵ Ӽ  ν,  ޴ ⺻ 
    ϳ̴.

         $ nslookup
         Default Server:  ns.nobreak.com
         Address:  210.105.79.2
         > exit

    nslookup  ȭ Ʈ '>' ǥϰ
    '/etc/resolv.conf' ǵ ù ° Ӽ ⺻  
    Ѵ. 'nslookup' BIND ޸ ϳ  ǿ ϱ
     'Default NS -> Timeout -> Error'  Ѵ.

      ˻

    nslookup ⺻ Էµ ο  A ڵ带 ˻ϰ, IP
    ּ(in-addr.arpa) ؼ PTR ڵ带 ˻Ѵ. 'set type=RR'
     A ڵ ̿ ڵ  ˻  , RR(Resource
    Record) A,ANY,CNAME,HINFO,MX,NS,PTR,SOA,TXT    ִ.
     ANY õ ڵ  ϶  ȣ̴.

         > www.kr.freebsd.org.                 # IP ˻
         Name:    www.kr.freebsd.org
         Address:  150.183.110.39

         > ftp.kr.freebsd.org.
         Name:    www.kr.freebsd.org           # ftp www CNAME
         Address:  150.183.110.39
         Aliases:  ftp.kr.freebsd.org

         > 150.183.110.39                      #  ˻
         Name:    www.kr.freebsd.org
         Address:  150.183.110.39

         > set type=MX                         # MX ڵ ˻
         > kr.freebsd.org.
         kr.freebsd.org  preference = 10, mail exchanger = mail.kr.freebsd.org

         > set type=NS                         # NS ڵ ˻
         > kr.freebsd.org.                     #   Ȯ
         kr.freebsd.org     nameserver = ns.kr.freebsd.org
         kr.freebsd.org     nameserver = ns2.kr.freebsd.org
         ns.kr.freebsd.org  internet address = 150.183.110.2
         ns2.kr.freebsd.org internet address = 150.183.110.3

         > 46.102.39.in-addr.arpa.             # ι   Ȯ
         kr.freebsd.org     nameserver = ns.kr.freebsd.org
         kr.freebsd.org     nameserver = ns2.kr.freebsd.org
         ns.kr.freebsd.org  internet address = 150.183.110.2
         ns2.kr.freebsd.org internet address = 150.183.110.3

    ⺻   

    nslookup ⺻ recurse  ϱ ,  ش
     Authority  Ư Ӽ  Ǹ Ͽ
    Authoritative (Ӽ ĳ ƴ) Ȯ  ʿ䰡
    ִ. 'server', 'lserver'  ⺻     
    ִ.   ־ Ӽ ּ( ƴ) ã 
       ε, 'server'  ⺻  ϰ,
    'lserver' ý ⺻ (nslookup  ʱ Ǵ)
     ٸ. 'lserver' Ÿ Ӽ Ī  , ٽ
    ٸ Ӽ ĪϷ ϴµ,  Ӽ  ʾ
    ش Ӽ ּҸ ˻   Ѵ.  .

         $ nslookup
         Default Server:  ns.nobreak.com
         Address:  210.105.79.2

    nslookup  ⺻  'ns.nobreak.com' 'lserver' ɿ
    ־ NS ּҸ ã   ȴ.

         > server ns.jp.freebsd.org.        # ⺻  
         Default Server:  ns.jp.freebsd.org
         Address:  199.100.7.25

         > server ns.nobreak.com.
         *** Can't find address for server ns.nobreak.com: Non-existent host/domain

    ns.jp.freebsd.org  ns.nobreak.com ã  . ̶
    'lserver'  ý ⺻   'ns.nobreak.com'
    ּҸ ˻Ѵ.

         > lserver ns.nobreak.com.
         Default Server:  ns.nobreak.com
         Address:  210.105.79.2

    Ʈ Ӽ   ϰ  ,  'root' 
      ִ.

         > root
         Default Server:  a.root-servers.net
         Address:  198.41.0.4

     ó ϱ

    Ӽ Resolver û óϱ , ӽ̽
    ˻ϸ,  Ӽ  ϴµ, nslookup  
    ƺ . Ӽ ͳݻ󿡼  ϸ,
    Ӽ   ǵ ߻ϰ,   
    ϴ, ü     ̴.

    [Image]
    [׸ 7] Ӽó ϱ

         (1)
         > set norecurse     # Iterative  ȯ
         > www.kr.freebsd.org.
         Server:  ns.nobreak.com
         Address:  210.105.79.2

         Name:    www.kr.freebsd.org
         Served by:
         - H.ROOT-SERVERS.NET
                   128.63.2.53
                   ORG
         - B.ROOT-SERVERS.NET
                   128.9.0.107
                   ORG
         ...

    'ORG.' Ǵ Ʈ   ۷ ش.

         (2)
         > server h.root-servers.net.
         > www.kr.freebsd.org.
         Server:  h.root-servers.net
         Address:  128.63.2.53

         Name:    www.kr.freebsd.org
         Served by:
         - WHO.CDROM.COM
                   204.216.27.3
                   FREEBSD.ORG
         - NS1.CRL.COM
                   165.113.1.36
                   FREEBSD.ORG
         - NS2.CRL.COM
                   165.113.61.37
                   FREEBSD.ORG

         (3)
         > server who.cdrom.com.
         > www.kr.freebsd.org.
         Server:  who.cdrom.com
         Address:  204.216.27.3

         Name:    www.kr.freebsd.org
         Served by:
         - ns.kr.freebsd.org
                   150.183.110.2
                   kr.freebsd.org
         - ns2.kr.freebsd.org
                   150.183.110.3
                   kr.freebsd.org

         (4)
         > server ns.kr.freebsd.org.
         > www.kr.freebsd.org.
         Server:  ns.kr.freebsd.org
         Address:  150.183.110.2

         Name:    www.kr.freebsd.org
         Address:  150.183.110.39

    Zone Transfer

    ش  Zone  纻 , Primaryκ Zone
    ͺ̽  ۾ Zone Transfer Ѵ.  ۾ ַ
    Secondary NS  ̷,  󸶳   ȣƮ
    ϵǾ ִ Ȥ Zone   ˻ϱ  ڰ
     ϱ⵵ Ѵ. Zone Transfer Authority 
    Ӽ  Ͽ ϹǷ, nslookup 󿡼 ش NS 
     , 'ls'  Ѵ.

         > server ns.kr.freebsd.org.
         > ls -t A kr.freebsd.org      # A ڵ 
          kr.freebsd.org.                server = ns.kr.freebsd.org
          kr.freebsd.org.                server = ns2.kr.freebsd.org
          mail                           150.183.110.32
          mqueue                         150.183.110.33
          www                            150.183.110.39
          www2                           150.183.110.40

         > ls -d kr.freebsd.org        #  ڵ 
          kr.freebsd.org.                SOA   ns.nobreak.com hostmaster.kr.freebsd.org.
                                         (1999031501 21600 1800 1209600 86400)
          kr.freebsd.org.                NS    ns.nobreak.com
          kr.freebsd.org.                NS    ns2.nobreak.com
          kr.freebsd.org.                MX    10   mail.kr.freebsd.org
          kr.freebsd.org.                MX    20   mqueue.kr.freebsd.org
          cvsup                          CNAME www.kr.freebsd.org
          mail                           A     150.183.110.32
          mqueue                         A     150.183.110.33
          ftp                            CNAME www.kr.freebsd.org
          ftp2                           CNAME www2.kr.freebsd.org
          ftp3                           CNAME ftp.free.nobreak.com
          www                            A     150.183.110.39
          www                            HINFO Pentium-200  FreeBSD 2.2.8
          www                            TXT  "Korea FreeBSD Users Group"
          www2                           A     150.183.110.40
          www2                           HINFO Pentium-133MHz  FreeBSD 2.2.8
          www2                           TXT  "Korea FreeBSD Users Group"

         > ls -t MX kr.freebsd.org > MX-kr.freebsd.org   # Ϸ 
         > view MX-kr.freebsd.org                        #   Ȯ

    BIND  'named-xfer' ܺ α׷  Zone Transfer
    Ѵ. Ӽ 忡 Ʈ Ͽ Secondary  
     ó 캸.

         secondary       kr.freebsd.org  210.105.79.2    sec-kr.freebsd.org

    BIND 'secondary'      Ѵ.

         loop(Interval == TTL) {
                 named-xfer -z kr.freebsd.org -f /var/named/sec-kr.freebsd.org -s Current_Serial 210.105.79.2
                 switch ( $? ) {      // 'named-xfer' ȯ  '$?'  
                         case 0 : OK; // ø , Zone Transfer ʿġ 
                         case 1 : OK; // ø , Zone Transfer  
                         case 2 : ERROR; // Ӽ ã  
                                         // Ȥ Ӽ  Authority  
                         case 3 : ERROR: // ø ,  ī 
                 }
                 primary  kr.freebsd.org  sec-kr.freebsd.org
         }

       (: Secondary NS's IP) Zone
    Transfer ϰ Ѵٸ, Primary NS ƮϿ  
    ɼ ش. (Zone Transfer ϴ ̱ , ȣƮ
       ȴ)

         xfrnets  210.105.79.3&255.255.255.255  210.105.80.128&255.255.255.128

    ̰ BIND-4 ε, IP 210.105.79.3 210.105.80.129-254
     Zone Transfer ϶ ǹ̴. BIND-4  IP
        "IP&Mask"  
    ۼϸ, Ŭ ü ϰ  쿣 '210.105.79.0' 
    ũ Ͽ ȴ.

         options {
                 allow-transfer { localnets; 210.105.79.3; };
         };

    BIND-8 쿡 ش   Ʈũ, 210.105.79.3
     ̴. localnets ̸ ٸ δ any, none,
    localhost  ִ.

    ʱȭ  '.nslookuprc'

    nslookup  '~/.nslookuprc'  ϸ,  о
    ɼ Ѵ. Ź ϴ ɼ ִٸ,   
    ȭ  ְڴ.

         * .nslookuprc  
         set type=NS
         set nosearch
         set debug

    DIG

    Dig(Domain Information Groper)  ݸ ¤ .
    'nslookup'  ̴ ũ ,  ϰ, 
    Ͽ, Shell Script ַ ȴ. 
    ns.kornet.ne.kr  www.nobreak.com A ڵ带 ˻
    ̴.

         $ dig [@Ӽ]  [Ÿ] [+ɼ]
         $ dig  @ns.kornet.ne.kr  www.nobreak.com  A
         ;; ANSWER SECTION:
         www.nobreak.com.        16h12m36s IN CNAME  ns.nobreak.com.
         ns.nobreak.com.         1d19h12m27s IN A  210.105.79.2
         ;; AUTHORITY SECTION:
         nobreak.com.            22h17m35s IN NS  ns.nobreak.com.
         nobreak.com.            22h17m35s IN NS  ns2.nobreak.com.
         ;; ADDITIONAL SECTION:
         ns.nobreak.com.         1d19h12m27s IN A  210.105.79.2
         NS2.nobreak.com.        1d1h46m58s IN A  210.105.79.3

    DIG    ANSWER SECTION, ش  
     Ӽ  AUTHORITY SECTION, ׸, ۷緹ڵ 
      ׿  ADDITIONAL SECTION Ͽ ش.

    DNSWALK

    Dnswalk Perl ۵ ũƮν  ʴ ȣƮ
    Ű MX, PTR  A, ߸ CNAME, ȿ  ̸,
     Ʈϸ Ʈ, ʿ䳪 ۷ ڵ, Lame Delegation  Zone
    ͺ̽ پ  ãش. ó ߰ġ  
    ϴµ   ̴. Dnswalk ֽ   ּҿ
      ִ.

       * http://www.cis.ohio-state.edu/~barr/dnswalk/

         $ dnswalk -raFl freebsd.org.
         Checking freebsd.org.
         Getting zone transfer of freebsd.org. from ns2.iafrica.com...done.
         SOA=implode.root.com    contact=hostmaster.freebsd.org
         FAIL: Cannot get SOA record for pt.freebsd.org from zeus.ci.ua.pt
         (lame?): Connection refused
         BAD: lv.freebsd.org NS ns.fasts.com: lame NS delegation
         BAD: eu.freebsd.org NS server.zsb.th-darmstadt.de: unknown host
         WARN: irc3.freebsd.org CNAME irc.nocturnal.net: CNAME (to nocturnal.net)
         WARN: ns.th.freebsd.org A 203.154.230.20: no PTR record
         WARN: irc2.freebsd.org CNAME va.i-Plus.net: unknown host
         1 failures, 3 warnings, 1 errors.

    Dnswalk ˻縦 ϱ  ش  Zone Transfer  
     Dig Resolver ƾ Ѵ. Delegation 
    󰡸 ˻縦 ϱ  Ŵ  Ѵٸ ѹ
    غ ϴ.

    Miscellaneous

    FQDN(Fully Qualified Domain Name)

    FQDN Ȯ  ǥ ĪѴ.  Ʈ ġ 
    θ 䱸ϸ, 'YAHOO.COM.' Է, 'WWW.YAHOO.COM.'
    Է ȣϴ. ׷ ̷ ȣ ϱ  FQDN̶
    ܾ ϸ, ̴ Namespace 󿡼  ȣƮ ϴ
    θ Ѵ.

         www(ȣƮ), yahoo.com.(θ), www.yahoo.com.(FQDN)

    Ģ  ǥ ӽ̽ θ Ȯ ϱ 
     Ʈ('.' Ʈ ) Ͽ ,  Ʈ
    ϰ Ѵ.

    DNS BIND 

    DNS Domain Name System ڷν, л ̹ ý Ѵ.
      Ǯ, θ IP ּҷ ȯִ ̴. ,
    ͳݿ ϴ  Ӽ    Ϻκ
    ϰ,  䱸ϴ Ŭ̾Ʈ Resolver Ģ  л
    ڷ ϴ  ã  ִ ý,   DNS  Ѵ.

    BIND Berkeley Internet Name Domain ڷ, DNS 
    Ʈ ϳ̸鼭, 'ũ'̶ ܾó DNS 
    Ʈ Īϴ  ̱⵵ Ѵ. BIND  
    ÷ õǾ,  θ ȴ.

    BIND-4(Traditional) BIND-8(Next Generation) 

    BIND 1999 1  BIND-4 BIND-8   Ѵ. 1998
    5 11   4.9.7 Ǹ  BIND-4 
    Ǿ, BIND-8   8.1.2 ϰ ִ. BIND-8
    RFC2136, RFC1996 Ͽ Ŀ  ũ Ǿ
    ǥǾ.  BIND-8 Űܰ ,  κ 
    ޴ OS  Ⱓ  BIND-4 ϰ Ƿ, 
     ε Ⱓ   ȴ. ,  帧
    BIND-8 Ѿ ִ.

    BIND-4 BIND-8 ܺ ̴, Ʈ  ȭ̴.
    BIND-4 Ʈ  named.boot ̰, BIND-8 named.conf
    ̴.  Ʈ  ۼ  ̰ ִ. Ÿ Zone ϰ
    ĳ   ϹǷ, BIND-4 BIND-8 ̱׷̼
    Ʈ ġϰ, Ʈ  ϴ  ϴ.

    Public Domain

     ̶ ϸ ۺ  Ѵ. ̴ ͳ 𿡼
     ϵ ӽ̽   ִ  Ѵ.
    , ӽ̽ ũ    Ӽ Ͽ
    ش Ӽ   resolvingϴ 츦 ϰ ã 
       ȴ. 系 ȵ  Ȥ ȴ.

    CNAME 뿡 

    CNAME  ο   DNS  ٸ ǰ δ. A
    ڵ常 ڴ ǰߵ ִ. Ư, CNAME CNAME ϴ
    쿡 ؼ  ڷḶ 'ȴ/ȵȴ'   ǰ 
    ְ, ʱ RFC ̸ ϰ ִ. , BIND
    implementation ̸   Ȯϰ ִµ ̴ Ÿ
     񽺸 Aliasingϴ 츦 Ͽ, CNAME ڵ ſ
      ̰ Ư ȣƮ IP Ǿ  õ
    ڵ带 ãƴٴϸ  ϱ ٴ, CNAME Ͽ 
    ڵ   ı޽Ű   ϰ ȿ̱
    ̴. CNAME ڵ (MX, SOA, NS ڵ 
    ʴ°) ؼѴٸ CNAME ſ ϰ Ȱ   
    Ѵ.

    Zone ͺ̽ ۼ 

    Ϲ  Ģ ؼ Zone ͺ̽ ۼϸ Ǽ
    ̴µ  ȴ.

      1. TAB   . ̰  ڵ带 ãµ 
         ȴ.
      2. TTL   ʴ ϰų 2D, 1W  
         ȣ  Ϸ Ѵ.
      3. ȣƮ Ǵ    ȣƮ ϰų, 
         FQDN ǥѴ.

              ftp                     IN      MX      mail
              www                     IN      CNAME   power

              ftp.nobreak.com.        IN      MX      mail.nobreak.com.
              www.nobreak.com.        IN      CNAME   power.nobreak.com.

         Ȥ  ȣƮ  FQDN ǥѴ. Ÿ 
         ȣƮ CNAME  찡 ֱ  ̰ 
         Ϲ̰  ȴ.

              ftp                     IN      MX      mail.nobreak.com.
              www                     IN      CNAME   power.nobreak.com.

      4. ϸ, ĺ  Ͽ, ߺ ǵǴ κ
          Ѵ.

    ۷ ڵ (Glue Record)

    ۷ ڵ NS ڵ ڷ ־ A ڵ带 ϸ,
    Ӽ ƮƮ  Ѵ.  
    'ns.nms.nobreak.com' ۷ ڵ̴.

         nms.nobreak.com.        IN      NS      ns.nms.nobreak.com.
         ns.nms.nobreak.com.     IN      A       150.183.110.2 ; Glue Record

    ,   ܺο Ǵ Ӽ  
    쿣, 'freebsd.org' NS 'ns.kr.freebsd.org'  ۷
    ڵ带 ̹ ǵǾ , ߺ ۷ ڵ带 Ͽ
    ȵȴ.

         nms.nobreak.com.        IN      NS      ns.kr.freebsd.org.  (X) ߺ ۷ ڵ

    ߺ ۷ ڵ Ӽ ο IP ּҷ Űų
      ư Ѵ.

    Lame Delegation

    Lame delegation̶ Namespace 󿡼  ũ Ѵ.

         nms.nobreak.com         IN      NS      ns.nms.nobreak.com.
                                 IN      NS      ns2.nms.nobreak.com.

     'nms.nobreak.com'     Ӽ ,
       ϳ Ȥ ΰ ش ο  Authority 
    ʴ ,  Primary, Secondary  ȵǾ  찡 Lame
    delegation شȴ.

    'Authoritative answer' 'Non-authoritative answer'

    Name Server ǿ   ĳ ϰ ֱ  
    ǰ 䱸Ǿ  Namespace  ʰ ĳ ڷ 
    Ѵ. ĳ ڷ Resolving  TTL(Time To Live) ð
    ȿ ȿϰ, TTL Ŀ ıȴ. Ŭ̾Ʈ 
    Resolving û Ӽ ĳ ڷ   
    'Non-authoritative answer'̰, ĳ ڷᰡ ų, ڷ TTL
    Ǿ ش  Primary Ӽ  ڷḦ  亯
    ־ 찡 'Authoritative answer'̴.

    Positive & Negative Caching

     Ȱ Resolving û    κ ߺȴ.

         $ finger @kfug.kr.freebsd.org
         $ talk nobreak@kfug.kr.freebsd.org

    , Ӽ ѹ ˻   ĳ Ͽ, Ŀ
    û  Ǹ ȿ óϵ Ǿ ִ. ׷ٸ,
     ʴ ο  û  ұ? Ϲ ߸
    ο  û  ߺȴ.    Ӽ 
      ŽϹǷ, ʿ ͳ Ʈ  
    ȴ. , Ӽ ̷ ߸   
    ĳϿ ʿ Ʈ Ѵ. ̸ Negative ĳ̶ ϸ,
    ݴ ˻ Ǵ ο  ĳ Positive ĳ̶ Ѵ.

    , Ӽ ĳ  ,  ʱ 
    'named' ϸ ĳ Բ . , ϸ Zone
    ͺ̽ Ŀ (kill -HUP xxxx) ñ׳ ̿ϵ
    Ѵ.

    Iterative(Nonrecursive) & Recursive Ӽ

    Ӽ Recursive   , Ŭ̾Ʈ(̸ 'Stub
    Resolver' Ѵ) û  Namespace ˻ 
    Ѵ.  Iterative 忡    (ڽ
     ʴ ο  û) ,   NS 
    Ѵ. κ Ӽ Recursive  ϸ, Iterative
     Ʈ  Ӽ  Ӽ(Ӽ
    ſ Iterative 尡 )  Ʈ 
    Ѵ. , Ŭ̾Ʈ Iterative   Ӽ
      Ƿ, Ӽ (:resolv.conf,  DNS
    ã) ߰Ͽ  ȴ. BIND-4 ƮϿ 'options
    no-recursion' ߰ν, Iterative  ȯ  ְ,
    BIND-8 쿣 options Ʈ 'recursion no;' Ѵ.

    RTT(Round Trip Time) Nameserver 

    Ӽ , 信 ҿǴ ð Round Trip Time̶
    Ѵ.(Recursive Ͽ  ˻ ð ƴϴ) BIND
     Ÿ Ӽ  RTT  ϰ ִٰ, û
    ο ټ Authority NS  RTT    Ӽ
     Ѵ. Authority NS鿡  RTT  
    쿣, ش Ӽ ü (ÿ)   
     Բ ΰ RTT Ѵ. RTT  ʹ,
    ش ο  û RTT      .
    ,    Ǵ  ,  
      ش Ӽ  RTT ݾ Ų.

    ϵī ( RFC1034 p25)

    Zone ͺ̽   ϵī(*)  ȴ.

         *               IN      A       210.105.79.20

    ϵī 'Zone Ÿ  ȣƮ' εǹǷ, Zone
     ȣƮ鿡 Ǹ Ͽ  ȴ. ̿ õ 
    Ǽ   MX ڵ ̴.

         *               IN      MX      mail

    ڴ  ȣƮ ޵Ǵ  Ѱ  ,
    ϵī MX Ͽ, ̰    
    ̴.   ϱ ؼ  ȣƮ MX ڵ带
    ߰Ͽ Ѵ.    ǵ  ȣƮ 
     Ѱ  ̴. (   ִ)

    , ϵī ȣƮ(   ϴ)θ  
    ִ.  .

         www.*           IN      A       210.105.79.20

    'www.ANYTHING.nobreak.com'  Ͽ,  ⸷
    ̵    ʴ´.

    Serial Number 

    Ŵ  ϴ ޴ Ǽ  ϳ 
    Ʈ۾  ߸ Serial ѹ̴. Ϲ 
    'YYYYMMDDNN' ǥδ 4294 ǥ⸦   ִµ,
    19990205010  Ǽ Ե '0' ش ʵ带 ÷ο
    Ų.  Secondary Zone Ⱓ Ʈ   ִ.
       ذ  ִ.

      1. Secondary  Ѵٸ,  Primary Zone Serial
          Ѵ. Secondary Ǿ ִ Zone (Zone
         Transfer)  BIND  Ѵ.
      2. Secondary Ÿ  Ǿ   Ұ ,
         Zone Serial '0' Ѵ. Secondary '0' Serial
          Zone ؼ,  Ʈ ϹǷ, Refresh
         ֱ⸸ŭ ٸ , ٽ  Serial ϸ ȴ.

         nslookup  -type=SOA  kr.freebsd.org  ns2.nobreak.com

    Secondry  ִ ش Zone Serial ȣ   Ȯ 
    ִ.

    IP   TTL 

     ǰִ Ʈũ ߿  ȴٸ,  
    ش ȣƮ TTL ӽ÷ 10(6000sec)  ߾ δ 
    .

         www     6000    IN      A       210.105.79.6

    Ÿ Ӽ ƿ ĳ ʵ ϱ  TTL 0 ϴ
    ͵  , Ŭ̾Ʈ ش  ＼  
    ݺǴ Resolving ϱ , ٶ  ƴϴ.
    Maximum Propagation Delay Time( TTL +  SOA Refresh)
    ŭ ٸ , ۾(IP )ϸ Ǵµ,  Ʈũ
     ۵Ǹ ġ  ߰ ̵ ߻ϹǷ, Ʈũ
     Ķ, 1-2  ڿ TTL  ϴ  . ش
    Zone   ȣƮ  쿣, SOA ڵ Minimum
    Ͽ Ϸ   ְڴ.

    ̷    (Load Sharing Between Mirrored Servers)

     Ʈ   ,  ذåν ټ ̷
     Ͽ, ϸ дŰ    ִ. ,
    ̷  ̷  ڿ ȫϿ  ϰ
    ̵ϴµ   ð ҿǰ,   й踦
    ϱⰡ ̵  ִ. ׷ ȭ ǥ ȣ 񽺿
    ,  û  ̷  ִ ǥ 
      ִµ, ⿡   ҰѴ. Shuffle
    Addresses̶ Ҹ  Ư  BIND 4.9  ȴ.

         www             180     IN      A       210.105.79.101
                         180     IN      A       210.105.79.102
                         180     IN      A       210.105.79.103

    ϳ ȣƮ  IPּҸ ־ , Ӽ ش
    ο     κ   Ѵ.

         $ nslookup www.nobreak.com
         Name:    www.nobreak.com
         Addresses:  210.105.79.101, 210.105.79.102, 210.105.79.103

         $ nslookup www.nobreak.com
         Name:    www.nobreak.com
         Addresses:  210.105.79.102, 210.105.79.103, 210.105.79.101

         $ nslookup www.nobreak.com
         Name:    www.nobreak.com
         Addresses:  210.105.79.103, 210.105.79.101, 210.105.79.102

    ̰ ε ߷(Load Balancing) ƴ, Ŭ̾Ʈ 3
      ϰ ӵǹǷ, ϸ ϴ ȿ  
    ְ,  ܺηδ ǥ θ ˸ ǹǷ,  Ȯ 
    ҿ ϴ.      κ 
    ʴ Ӽ Ͽ TTL  å(TTL Ͽ ٽ û
    )ϴ ͵ .

    ϳ δ ټ CNAME ϴ ̴. Ģ
    ټ CNAME źεǱ , ݵ   Ʈ Ͽ
     ɼ ־ Ѵ.

         options {
                 multiple-cnames yes;
         };

    ̰ BIND-8  ϸ, ǥ YAHOO(www.yahoo.com)
    ̷  ȴ.

         www             180     IN      CNAME   www1.nobreak.com.
                         180     IN      CNAME   www2.nobreak.com.
                         180     IN      CNAME   www3.nobreak.com.
         www1            180     IN      A       210.105.79.101
         www2            180     IN      A       210.105.79.102
         www3            180     IN      A       210.105.79.103

    ټ A ڵ  Resolver  NS Authority NS ټ
    IP( κ) Ѱܹ޾ ĳ    üε
     κó , ټ CNAME   NS  
    ּҸ Ѱܹޱ  ü  κ Ұϸ, TTL
      ش Resolver ϳ ּҸ ϰ ȴ.

         * Authority NS  Ͽ 
         $ nslookup  www.nobreak.com  ns.nobreak.com
         Name:    www1.nobreak.com
         Address:  210.105.79.101
         Aliases:  www.nobreak.com

         $ nslookup  www.nobreak.com  ns.nobreak.com
         Name:    www2.nobreak.com
         Address:  210.105.79.102
         Aliases:  www.nobreak.com

         $ nslookup  www.nobreak.com  ns.nobreak.com
         Name:    www3.nobreak.com
         Address:  210.105.79.103
         Aliases:  www.nobreak.com

         * NS ĳ ޾ƿ 
         $ nslookup  www.nobreak.com  ns.kornet.ne.kr
         Name:    www2.nobreak.com
         Address:  210.105.79.102
         Aliases:  www.nobreak.com

         $ nslookup  www.nobreak.com  ns.kornet.ne.kr
         Non-authoritative answer:
         Name:    www2.nobreak.com
         Address:  210.105.79.102
         Aliases:  www.nobreak.com

    , ε ߷ ϱ ؼ ý Ͽ 
     ϴ 谡  ʿϴ.

     

      1. Paul Albitz & Cricket Liu, "DNS and BIND 3rd Edition",
         O'Reilly & Associates, Inc., ISBN 1-56592-512-2, Sep 1998
      2. Paul Albitz, Matt Larson & Cricket Liu, "DNS on Windows NT",
         O'Reilly & Associates, ISBN 1-56592-511-4, Oct 1998
      3. Bryan Costales & Eric Allman, "sendmail 2nd Edition", O'Reilly
         & Associates, ISBN 1-56592-222-0, Jan 1997
      4. Bryan Costales & Eric Allman, "sendmail Desktop Reference",
         O'Reilly & Associates, ISBN 1-56592-278-6, Mar 1997
      5. H. Eidnes, G. de Groot & P. Vixie, "Classless IN-ADDR.ARPA
         delegation", RFC2317, Mar 1998
      6. M. Andrews, "Negative Caching of DNS Queries (DNS NCACHE)",
         RFC2308, Mar 1998
      7. O. Vaughan, "A Legal Basis for Domain Name Allocation",
         RFC2240, Nov 1997
      8. M. Hamilton, "Use of DNS Aliases for Network Services",
         RFC2219, Oct 1997
      9. R. Elz, R. Bush & S. Bradner, "Selection and Operation of
         Secondary DNS Servers", RFC2182, Jul 1997
     10. S. Thomson, Y. Rekhter & J. Bound, "Dynamic Updates in the
         Domain Name System (DNS UPDATE)", RFC2136, Apr 1997
     11. P. Vixie, "A Mechanism for Prompt Notification of Zone Changes
         (DNS NOTIFY)", RFC1996, Aug 1996
     12. C. Everhart, L. Mamakos & R. Ullmann, "New DNS RR
         Definitions", RFC1183, Oct 1990
     13. P. Mockapetris, "Domain Names - Implementation and
         Specification", RFC1035, Nov 1987
     14. P. Mockapetris, "Domain Names - Concepts and Facilities",
         RFC1034, Nov 1987
     15. M. Lottor, "Domain Administrators Operations Guide", RFC1033,
         Nov 1987
     16. M. Stahl, "Domain Administrators Guide", RFC1032, Nov 1987
