Company Network Running Windows 2003 on 2 Servers for DNS.
Using Private IP's Internally, NAT through PIX 515E Firewall to Cisco 2610 Router with 2 T1's load balancing to different networks. clients running DHCP.
The configuration was working. Something has affected DNS resolution to certain domains and hosts. The only factors that have knowingly changed is the addition of a second (different homed) T1 line, although tried to eliminate this by shutting down the interface on the router to the second T1, giving us the network config of the working config. Most sites work fine.
The problem manifested itself in users being unable to access www.yahoo.com or www.bbcnews.com (can access websites via IP's).
Forwarders are set up in MS DNS for All Domains (unresolveable). NSLookup can get a record for the domain (yahoo.com) but not for www.yahoo.com (this request times-out, without ever going to the next DNS server). There are no entries/zones for yahoo anywhere in our DNS infrastructure. I have verified and bypassed by hardcoding one of our ISP's DNS servers on an internal computer... it works flawlessly. So somewhere the server(s) is not forwarding the request. I even attempted setting up a specific forwarder in DNS for the domain yahoo.com with its DNS servers listed... but to no avail (although in NSLookup, it did attempt contact through yahoo.com's DNS servers before reverting back to our internal server at which point it timed-out.)
Any ideas? Any addition information required?
Thanks in advance.