2.
Internet DNS DNS UUCP (JUNET ) ( ) mailconf
( )
DNS name [ttl[ ttl] ] IN type value... < > << > type (A, MX, CNAME,...) value
A (Address) RR (Resource Record) IP IP MX (Mail exchanger) ) RR CNAME (Canonical NAME) RR
IP (A RR) IN A IP mail.x.co.jp jp.. IN A 12.34.56.78 user@mail.x.co.jp
DNS nslookup dig host dnsquery bind
nslookupa(1) % nslookup sh.wide.ad..wide.ad.jp. Server: localhost Address: 127.0.0.1 Name: sh.wide.ad..wide.ad.jp Address: 203.178.137.73
IP mail.x.co.jp IN A 12.34.56.78 IN A 12.34.54.32 ( ) DNS (?)
nslookupa(2) % nslookup jp-gate.wide.ad..wide.ad.jp Server: localhost Address: 127.0.0.1 Name: jp-gate.wide.ad..wide.ad.jp. Addresses: 203.178.137.17, 203.178.136.81, 203.178.137.75, 203.178.136.89
Generic MX (Mail exchanger) ) RR IN MX x.co.jp jp.. IN MX 10 mail.x.co.jp jp. user@x.co.jp MX A
nslookupmx % nslookup -q=mx wide.ad.jp jp. Server: localhost Address: 127.0.0.1 wide.ad.jp preference = 10, mail exchanger = sh.wide.ad..wide.ad.jp : sh.wide.ad..wide.ad.jp internet address = 203.178.137.73 (additional information)
(MX) x.co.jp jp. IN MX 10 mail1.x.co.jp jp. IN MX 50 mail2.x.co.jp jp. IN MX 100 mail.provider.ad.jp jp. ( ) mail1
MX MX RR Primary MX / Primary Mail Server First MX / First Mail Server Secondary MX / Secondary Mail Server Lower MX (( )
Lower MX MX RR sendmail -bt $= $=w MX RR RR Lower MX
x.co.jp jp. IN MX 10 mail1.x.co.jp jp. IN MX 10 mail2.x.co.jp jp. A RR IP IP spool full MX
MX A Secondary MX IP IP A ( ) DNS ( )
MX (cont.) *.x.co. x.co.jp.. IN MX 10 mail.x.co.jp jp. Firewall ( ) : : root Wildcard MX nohost.x.co..x.co.jp host. host.nosubdom.x.co..x.co.jp
MX (cont d) specific ns.x.co..x.co.jp. IN A 12.34.56.78 *.x.co.jp jp. ns.x.co..x.co.jp. IN MX 10 mail.x.co.jp jp. IN MX 10 mail.x.co.jp jp.. (( ) MX
CNAME (Canonical NAME) RR ( ) archie.wide.ad..wide.ad.jp (=sun3.tokyo tokyo.wide.ad..wide.ad.jp) pop.x.co.jp jp.. IN CNAME host1.x.co.jp jp. CNAME RR
CNAME RR (cont d) CNAME RR MX RR CNAME? A RR
nslookupcname % nslookup -q=cname archie.wide.ad..wide.ad.jp. Server: localhost Address: 127.0.0.1 archie.wide.ad..wide.ad.jp canonical name = sun3.tokyo tokyo.wide.ad..wide.ad.jp
DNS (cont.) 1. CNAME CNAME ( ) 2. MX preference MX A Additional Information
DNS (cont d) 3. A MX MX (Additional Info. A ) A 2 (MX A) MX
MX RR CNAME CNAME CNAME
(A-Z, a-z) (0-9) (-) ( ( _ ) RFC1035(S), RFC1123(S) (4.9.4 )bindresolver _ (res_hnok)
MX RR CNAME MX RR CNAME Lower MX MX RR named
CNAME (RFC1123(S)) ( )sendmail sendmail.cf MX A IETF CNAME (?)
CNAME CNAME RR CNAME RR alias1 alias2 RFC1034(S) IN CNAME alias2 IN CNAME real-name (should not) (should) sendmail 10 10 named 8 (MAXCNAMES) (MAXCNAMEDEPTH)
DNS - DNS -
(zone) my.domain.jp zone = *my.domain.jp
/etc/named.boot (bind 4.x) directory /etc/namedb primary my.domain.jp my.domain.zone /etc/named.conf conf (bind 8.x) options { directory "/etc/" /etc/namedb"; }; zone "my.domain.jp jp" " { file "my.domain.zone" my.domain.zone"; }; /etc/ /etc/namedb/my.domain.zone
(cont.) ; $ORIGIN $ my.domain.jp jp. @ IN SOA... IN NS ; my.domain.jp jp. a IN A... IN MX... ; a.my.domain.jp jp.
(cont d) MX/CNAME RR. $ORIGIN named.{boot,conf conf} @
SOA () NS @ IN SOA... ( 1997121703 ; Serial 3600... )
SIGHUP # ps aux grep named 65??... named # kill -HUP 65 ndc (name daemon control interface) # ndc reload
(DNS DNS )
named 4.9 (BIND_NOTIFY) SOA
FORCED_RELOAD SIGHUP named named-xfer # mv mydomain.zone mydomain.zone..zone.bak # ndc restart
MX ( )