Reverse DNS, in simple explanation it means that resolve your IP address into hostname. Nowaday it became a must have requirement for mail server’s IP address. It is also one of the method to determine your mail server IP is glue to the hostname.
Here is how to find out the reverse DNS IP address is pointed to which DNS server for zone delegation.
dig -x 126.96.36.199 ; <<>> DiG 9.6.0-APPLE-P2 <<>> -x 188.8.131.52 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 21938 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0 ;; QUESTION SECTION: ;184.108.40.206.in-addr.arpa. IN PTR ;; AUTHORITY SECTION: 136.175.in-addr.arpa. 10800 IN SOA ns1.tm.net.my. dnsadm.tmnet.com.my. 2011012113 10800 3600 604800 86400 ;; Query time: 37 msec ;; SERVER: 192.168.0.1#53(192.168.0.1) ;; WHEN: Sat Jan 22 19:39:12 2011 ;; MSG SIZE rcvd: 111
The result above shown
- The SOA record shown the IP Address is pointed to ns1.tm.net.my for reverse DNS delegation.
- The zone 136.175.in-addr.arpa is delegating the IP 220.127.116.11
This command is pretty useful when you want to find out is the reverse DNS delegation works correctly.