RMaxwell:

Try having your app write a script to feed to nslookup, then parse the answers. That way it should be quick only one invocation of nslookup. A sample nslookup run:

root@swill ~
$ nslookup
*** Can't find server name for address 192.168.0.1: Non-existent domai
+n
*** Default servers are not available
Default Server:  UnKnown
Address:  192.168.0.1

> set q=A
> 216.24.27.80
Server:  UnKnown
Address:  192.168.0.1

Name:    win.net
Address:  216.24.27.80

> 216.24.27.81
Server:  UnKnown
Address:  192.168.0.1

Name:    mail.digicove.com
Address:  216.24.27.81

>
[download]

It seems to be a simple task to parse out the Name:/Address: pairs.....

--roboticus