Our internal DNS server with windows 2003 has problems with querying specifically .co domains. I've done a Package capture and found that the DNS server does not do anything when querying .co domains(the others like .com .net etc are fine).
So I think this problem is related with the server cache. And when I look at the server cache, there's no A records for .co root name servers which might due to TTL. So I guess the cache stuck somewhere.
Once I clear the cache of the DNS server, it will no longer have the problem but after some time (I can't tell the exact time), the problem will appear again which is quite annoying.
Can anyone seen this before or help please?