DNS problems in Server 2003

My domain environment is no longer functioning. All of a sudden I could not access the Internet throughout our school network. Actually, web pages will open up, but after an extremely long period of time (maybe 5 minutes to load google.com). I Have two errors in DNS event log. First is The DNS server has encountered a critical error from the AD. Check that the AD is functioning properly. The second error is The DNS server was unable to complete directory service enumeration of zone cec.local. This DNS server is configured to use information obtained from AD for this zone and is unable to load the zone without it. Check that the AD is functioning properly and repeat enumeration of the zone.

I have two DNS servers  and both have existed for a couple of years. When I try to do an nslookup command from my workstation I get the following message: "Can't find server name for address (my DNS server): non-existent domain
Default server: unknown

How can I go about fixing this problem?

Thanks so much for your help.
skenny10IT ManagerAsked:
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Radhakrishnan RSenior Technical LeadCommented:
Make sure, from ISP side everything is fine and a reboot of the server can resolve the issue.
skenny10IT ManagerAuthor Commented:
ISP forwarder IP's are still the same. ISP says all is good.d  I have done a reboot and still same issue.
You mentioned you cannot resolve dns queries from a client machine, is it the same issue when you do an nslookup on the server?
What's DNS server is your servers set to use (is it using DNS forwarders or root hints)? It's possible that they are currently not working or decommissioned (depending on how the servers are setup). Try setting your server to use the google DNS servers to test (; if using DNS forwarders or if using root hints, check it's populated.
This can be done by opening Administrative Tools -> DNS -> right click on (server name) -> Properties.
If that works, lookup or check the status of the ISP DNS server.

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To fix the
: "Can't find server name for address (my DNS server): non-existent domain
Default server: unknown

Yo must create a reverse lookup zone in your DNS server  and register a PTR record for your servers

This can help you identifying the problem:
Also check the servers haven't had any major changes or issues (updates, disk space running out etc).
Do you use a proxy or the client computer have full access to the internet? Check from the proxy if there is a latency. And from the client run ipconfig /flushdns and then ping google.com, check how much time does it take for the name resolution. Also run tracert.

You can also try and change the DNS look up zones from Active Directory integrated to primary and then check if the error still occur.

For errors on the DC run the following commands:

dcdiag /v > dcdiag.txt  & dcdiag.txt


netdiag /v > netdiag.txt & netdiag.txt

Check if you see any errors or test failed.
Viral RathodConsultantCommented:
It seems that Reverse Look Zone is missing on the server

1)Please Create Reverse Lookup Zone
2) Run ipconfig /flushdns
3) ipconfig /registerdns
4) Restart the DNS service

After completing above steps on the server please try nslookup again and letus know the results.

Note : Make sure Primary DNS address on the server is pointed to Server IP Address .
skenny10IT ManagerAuthor Commented:
Thanks for your help
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