Making sure your DNS is properly configured is, at best, like making sure your girlfriend is propoerly configured, and at worst, like making sure your mother-in-law is properly configured. It amazes me that it has to be this complicated. Anyone have a nice GUI for configuring Linux DNS? I'll pay lots of money for one.
Your reverse DNS mapping (getting a host.domain name from an IP number) is more and more important. Many web sites will try to reverse DNS map you as they serve every page. My Wells Fargo Online Bill Pay is one such site that does this. When I didn't have my reverse DNS mapping set up correctly, the Wells Fargo site was EXTREMELY slow! As soon as I got it fixed, Wham-o!
Another important reason to get your reverse DNS set up correctly is so that you can download the 128-bit encryption version of Netscape Navigator from Netscape. They use reverse DNS mapping to verify that your computer is in the US or Canada, since this version of their browser has export restrictions.
I don't know exactly how to set up a reverse DNS map. I do know that the responsibility is usually handled by your ISP. The authority for who gets to reverse map what set of IP addresses is contained in some super double secret database that most people can't even access. It has to do with the assigning of IP numbers. You can't just make up an IP number and you can't just try to claim responsibility for reverse mapping a set of IP numbers.
I do have one file which looks suspiciously like it is related to reverse mapping. It is called named.rev:
> more /etc/named.rev
; /etc/named.rev
; modified 12/17/1996
;
;
$ORIGIN 42.0.209.IN-ADDR.ARPA.
@ IN SOA expocity.com. mckenna.koko.expocity.com. (
97071601 ; Serial
360000 ; Refresh: 100 hours
3600 ; Retry: 1 hour
3600000 ; Expire: 42 days
360000 ; Minimum: 100 hours
)
IN NS koko.expocity.com.
IN NS geo1.geo.net.
IN NS ns1.geo.net.
;
2 IN PTR koko.expocity.com.
3 IN PTR swan.expocity.com.
6 IN PTR janis.expocity.com.
7 IN PTR johnlee.expocity.com.
15 IN PTR aretha.expocity.com.
16 IN PTR ella.expocity.com.
;
;
; End of /etc/named.rev
Matt Ranney says "You can use 'dig'. Dig this:"> dig @koko.expocity.com expocity.com axfr | head -13 ; <<>> DiG 2.2 <<>> @koko.expocity.com expocity.com axfr ; (1 server found) expocity.com. 86400 SOA koko.expocity.com. mckenna.koko.expocity.com.expocity.com. ( 97072801 ; serial 10800 ; refresh (3 hours) 1800 ; retry (30 mins) 604800 ; expire (7 days) 86400 ) ; minimum (1 day) expocity.com. 86400 NS koko.expocity.com. expocity.com. 86400 NS geo1.geo.net. expocity.com. 86400 NS ns1.geo.net. expocity.com. 86400 MX 50 mail1.geo.net.expocity.com.(note the " | head -13 " is just to limit the output to the first 13 lines)
dig @mydnsserver.mydomain.com -x abc.def.ghi.jkl ; <<>> DiG 2.1 <<>> @ns1.geo.net -x ; (1 server found) ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10 ;; flags: qr aa rd ra; Ques: 1, Ans: 1, Auth: 2, Addit: 2 ;; QUESTIONS: ;; 2.42.0.209.in-addr.arpa, type = ANY, class = IN ;; ANSWERS: 2.42.0.209.in-addr.arpa. 86400 PTR koko.expocity.com. ;; AUTHORITY RECORDS: 42.0.209.in-addr.arpa. 86400 NS geo1.geo.net. 42.0.209.in-addr.arpa. 86400 NS ns1.geo.net. ;; ADDITIONAL RECORDS: geo1.geo.net. 14400 A 192.231.42.1 ns1.geo.net. 14400 A 192.231.42.2 ;; Total query time: 13 msec ;; FROM: koko to SERVER: ns1.geo.net 192.231.42.2 ;; WHEN: Tue Jul 29 09:16:34 1997 ;; MSG SIZE sent: 41 rcvd: 169
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