very, very, very interesting. I had the same error on a 2008 AD DS lab I setup. What's puzzling is that I disabled IP v6 before installing DNS on the box. So after reading MPalecek post I reenabled IP v6, went to the properties and changed it to obtain information automatically. Oh btw there was a wierd entry of "::01" as the DNS in IP v6. I applied the settings and disabled IP v6 again. Done! No more "Uknown" server. Also, a PTR entry was added in the Reverse Lookup zone for the server.
Actually, you don't want to disable IPv6. Microsoft has intergrated with the OS, and may break things if you do. Read the following for specifics:
Arguments against disabling IPv6
Demoire, [MSFT], 24 Nov 2010 12:37 AM
The Cable Guy - Support for IPv6 in Windows Server 2008 R2 and Windows 7, by Joseph Davies, Microsoft, Inc.
Quoted by Joseph Davies, MSFT:
"IPv6 is a mandatory part of the Windows operating system and it is enabled and included in standard Windows service and application testing during the operating system development process. Because Windows was designed specifically with IPv6 present, Microsoft does not perform any testing to determine the effects of disabling IPv6. If IPv6 is disabled on Windows Vista, Windows Server 2008, or later versions, some components will not function. "Moreover, applications that you might not think are using IPv6—such as Remote Assistance, HomeGroup, DirectAccess, and Windows Mail—could be."
As far as nslookup "unknown server" message (note: This is NOT an error), it's just trying to resolve the IP address nslookup is using in your reverse zone, but if you do not have a reverse zone for that subnet, or if you do and you do not have a PTR (reverse entry), nslookup is simply saying, I can't find the name, but let's move on and enter your query so I can resolve it for you.
If you do not want the "::1" address to show (after you re-enable IPv6), you can simple either change the protocol order so IPv4 is chosen first, or simply remove the "::1" out of the NIC, IPv6 properties.
Read my blog above which has specifics, which I pasted below for your convenience, please:
How to Disable RSS TCP Chimney Feature and IPv6 & Instructions to remove that "::1" IPv6 DNS address that shows up in an ipconfg /all
Should I Disable IPv6? No, Microsoft no longer recommendeds disabling IPv6.
If you want to change the protocol order so IPv4 is the preferred protocol, follow the instructions in the following link. You can even use the MrFixIt, which will do it for you, eliminating any mistakes:
How to disable IP version 6 (IPv6) or its specific components in Windows 7, in Windows Vista, in Windows Server 2008 R2, and in Windows Server 2008