DNS Strange Problem on Win XP

December 5 2009

The problem: IE,MSN,etc was not able to connect to Internet
History:
PC equipped with XP SP3 , belong to a business domain network.
Before the recent IT changes , PC was able to connect to Internet from my home DSL Line. The only thing i had to do is to go on IE and uncheck the usage of business proxy server.
After some IT changes, my PC was not able to connect to the internet any more from home (i tried even wireless or with cable).

Troubleshooting Steps:
1. IP Properties were set to "auto" (ip address , subnet mask , dns)
Changed DNS to something that i know it is working fine
No Conection Established.
2. Dos Mode - nslookup
In that mode , i saw that i was receiving a timeout error, the dns server was called "not available" but the IP of the DNS server was pointing somewhere to my office IP.
3. Dos mode : nslookup - 192.168.1.254 (the adress of a working dns server)
no result. After running nslookup, i saw in surprise that my PC was insisting to keep as dns server a business ip .... obviously the IP of the DNS Server in my office.

Solution
Open Registry , and go to the following path:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\
There i found the standard key/folder (everyone has this key) called Terminal Services.
In my case an EXTRA key/folder was existed there, called DNSClient, which was having the following items inside:
"AdapterDomainName"="mycompanyname.local"
"RegisterAdapterName"=dword:00000001
"RegistrationEnabled"=dword:00000001
"RegistrationOverwritesInConflict"=dword:00000001
"NameServer"="172.20.199.16"

I deleted the whole folder (DNSClient) after making an export of this key , and EVERYTHING WORKED FINE after a nice restart....

In case for some reason i have to put these folder back to the registry i can just click "merge" on the exported file just before deleting the key.

Tip : I had the oportunity before deleting the whole registry folder, to verify my action by looking to my old pc which was set up one year ago to be connected in a very similar domain network. So i verified that this DNS record was not existing in the refistry of my old pc , and pressing the "delete" key was more safe now....

Remark:
I found as well a difference in the txt file HOSTS (C:\windows\system32\drivers\etc)
IE looks first this file in case there are some correspondancies of IP addresses to domain names (something like manual DNS).
This file is good to have only one record:
127.0.0.1 localhost

In my case , some extra records were existed.... i deleted this records just in case.

I'm really happy now that my business PC is able to connect to my home DSL Lan without any problem....

Regards