I think what Corona meant was what DHCP software is running in the DHCP server from which your Solaris box is getting its IP address.
Start from the beginning:
Remove everything from resolv.conf but the line nameserver xxx.xxx.xxx.xxx
Check that /etc/nsswitch.conf has a line like: **
hosts: files dns
Can you actually ping the DNS servers from the Solaris box?
What happens when you do an nslookup on any outside website by name, like
www.internic.net?
Is there a proxy in your environment?
** I rarely work with DHCP in unix, so I'm not sure if you need nsswitch.conf whne using DHCP.