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-   -   Name to IP resolution works but not IP to name (https://www.linuxquestions.org/questions/linux-server-73/name-to-ip-resolution-works-but-not-ip-to-name-705711/)

brandon@rhiamet.com 02-18-2009 04:29 PM

Name to IP resolution works but not IP to name
 
I'm running a BIND server on a private network. All hostname lookups work, but I can't resolve any internal addresses to hostnames but can resolve external IP addresses to hostnames. For example,

$ host www.google.com
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.95.99
www.l.google.com has address 74.125.95.103
www.l.google.com has address 74.125.95.104
www.l.google.com has address 74.125.95.147
$ host 74.125.95.99
99.95.125.74.in-addr.arpa domain name pointer iw-in-f99.google.com.
$ host mail
mail.foo.com is an alias for maisrv01.foo.com.
maisrv01.foo.com has address 192.168.1.3
$ host 192.168.1.3
Host 3.1.168.192.in-addr.arpa not found: 3(NXDOMAIN)

I'm not sure where to look and haven't found anything in my searches. Any help is appreciated.

anomie 02-18-2009 04:32 PM

Start here: Basic DNS: PTR records and why you care

brandon@rhiamet.com 02-18-2009 04:44 PM

Beautiful. Thanks.

rweaver 02-18-2009 04:45 PM

Quote:

Originally Posted by brandon@rhiamet.com (Post 3448714)
I'm running a BIND server on a private network. All hostname lookups work, but I can't resolve any internal addresses to hostnames but can resolve external IP addresses to hostnames. For example,

$ host www.google.com
www.google.com is an alias for www.l.google.com.
www.l.google.com has address 74.125.95.99
www.l.google.com has address 74.125.95.103
www.l.google.com has address 74.125.95.104
www.l.google.com has address 74.125.95.147
$ host 74.125.95.99
99.95.125.74.in-addr.arpa domain name pointer iw-in-f99.google.com.
$ host mail
mail.foo.com is an alias for maisrv01.foo.com.
maisrv01.foo.com has address 192.168.1.3
$ host 192.168.1.3
Host 3.1.168.192.in-addr.arpa not found: 3(NXDOMAIN)

I'm not sure where to look and haven't found anything in my searches. Any help is appreciated.

Basically there are forward and reverse dns lookups.

A forward lookup resolves a name to an ip. Reverse does the opposite. When you're talking about mail for example reverse lookups matter because some servers will reject you or mark your mail as spam if you don't have your dns setup correctly. Then there is split horizon dns and all kinds of fun stuff related to that when you want dns to resolve correctly for both internal hosts and external hosts.

http://en.wikipedia.org/wiki/Reverse_DNS_lookup


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