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Secondary DNS server was not being asked for requests

Posted on 2006-07-17
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Last Modified: 2012-05-05
We have two DNS servers - DNS1 and DNS2.  Our primary DNS server went down over the weekend and our secondary server must not have been being servicing requests.  Shouldn't the client try the secondary DNS if it cannot reach the primary?
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Question by:scottvin
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by:grsteed
ID: 17123158
Yes if both are configured on the client.  Ipconfig /all will tell you.   If you're using DHCP it will be whatever the server is handing out for DNS.

Cheers,
Gary
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by:scottvin
ID: 17123341
They are both configured on the client.  However, they were not asking the secondary for requests.  What is the timeout for DNS requests?
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grsteed earned 500 total points
ID: 17123608
Not sure what the timeout is exactly but I think it's a matter of seconds.

Basically if it doesn't get a response from the preferred DNS server (the first on in the list) it will (should?) try the next one.

I just did a test on my PC (XP Pro) with Ethereal and it goes back and for with the DNS requests using one for a while and then the other.

Was the primary down hard?

Can you force your PC to use the secondary to see if it's responding? Try this

go to the  command prompt and enter NSLOOKUP.

enter SERVER w.x.y.z  (your secondary DNS)

then enter www.google.com  and see if you get the proper response.

Cheers,

Gary
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Author Comment

by:scottvin
ID: 17123730
Non-authoritative answer:
Name:    www.l.google.com
Addresses:  66.102.7.99, 66.102.7.104, 66.102.7.147
Aliases:  www.google.com

Worked fine.  Yes my primary was down hard.
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by:grsteed
ID: 17123766
hmmm,  not sure what to tell you.  And since it's not happening now (the primary is back up right?) There's not much else to do.

Maybe  someone else will chime in.

Cheers,
Gary
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by:scottvin
ID: 17123977
Yeah - It's back up.  Now I am hearing that is wasn't everyone.  I am going to have those particular users IP setting emailed to me.  Will let you know what I find.
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by:mjdeale
ID: 17124394
Try to Ping The secondary DNS sever from the client and see if you can ping. if you can Ping it than reboot the DNS server or the service and should work fine. if not than it's a hardware failure.

Mehdi,
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by:grsteed
ID: 17124506
Mehdi,

He was able to query and get a response from the secondary using nslookup as shown above so I think it's fine.

Cheers,
Gary
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by:Robin888
ID: 17127361
Hi scott,

I would suggest isolate and troubleshoot on the problem client computers. something might be blocking on the client computers.. try ipconfig /flushdns on those computers, ipconfig /release/renew, see if those command works. I agree with gary, the speed should be seconds switching from primary dns to secondary dns....
Try check event viewer on those problem client computers.
hmm maybe you have the problem isolated computers on different network?

R
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