Find the Hostname with IPAddress

[test@srinfosoa01 logs]$ nslookup srinfosoa01
Server:         128.166.33.44
Address:        128.166.33.44#53



nslookup 208.77.188.166 
...
Non-authoritative answer:

166.188.77.208.in-addr.arpa     name = www.example.com.