I am not able to join PC's with WinXP to my domain. I recently had a network-wide virus and whenever I try to add the PCs to the domain I get the "domain name cannot be found" error. I have checked my DNS, My Firewall, and the only thing that looks like it could be an issue is I have my Domain Controller serving as 1st DNS server and ISP DNS as Alternate. I am joined via VPN to another network and use their DNS servers on the router. NSLOOKUP cannot find name of my domain or DC but finds the IP for my DC. I can ping the DC via NETBios and IP but attempts to add computers to the domain have been fruitless. Any thoughts? Jared

I hope you mean XP Pro because XP Home just can't join domains. They can see shares but that's it. If that's not it, is the domain a .local domain? Does it have an internal IP address? If it does, then I wouldn't have the ISP's DNS as the alternate.

This is most certainly a problem with dns or a firewall, more than likely though dns. Check that the clients have the correct dns server ip setting and can do an nslookup for the domain controllers dns name (FQDN) (assuming you dns server is setup coorectly) Otherwise are you using the NETBIOS domain name? i.e. DOMAIN