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40960 and 40961 errors on workstations as they lose connections intermittently; DNS seems to change

Posted on 2007-12-03
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Last Modified: 2010-04-21
I think this is server related because the errors happen on more than one workstation - no errors in the server event logs.  Users intermittently (with one user it happens every afternoon almost like clockwork) get disconnected from the server/ad and usually restart and reconnect just fine.  They get 40960 and 40961 errors in the event logs.  I've tried various things in terms of registry settings, network card driver, etc., and can't seem to make them stop.  Unfortunately, this happens intermittently so my troubleshooting usually involves trying some changes and then coming back in a day or two to check logs and see if it happened again (which, so far, it always has).

Another thing - and this might be a clue:  On the problem workstations it seems that the DNS server changes.  The server is serving DHCP and DNS, and the only DNS entry according to the DHCP server is itself (192.168.1.2).  However, sometimes I will check a workstation with ipconfig /all and find that DNS has changed to two servers - the router (192.168.1.1) and one other external server.  Yet the DHCP is still showing as the server (192.168.1.2).  I don't frankly know how the DNS server can change on the fly.  I can do an ipconfig /release and ipconfig /renew and it comes back to 192.168.1.2 like it should be.  For my latest attempt, I hardcoded the DNS on a couple of computers to 192.168.1.2.  I'll check tomorrow and see if they've changed again!

Thanks in advance for any ideas.
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Question by:manassehkatz
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Netman66 earned 500 total points
ID: 20400482
Turn off DHCP on the router.

Make sure your system clocks are all properly set (time, time zone, DST and date) on the workstations AND all your servers.




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Expert Comment

by:ChiefIT
ID: 20433409
Hi Netman:
Hello manasehkatz:

I think your DNS problem and the two events you are looking at may not be correlated.

I think DNS records disapearing is related to the scavaging time being set at a lesser time than the DHCP lease renewal.

I am assuming a something on your network. That is, you have one fixed IP for your server and router. All other IPs are dynamic IPs from the DHCP server.

With that said, can you look up a couple settings for me?
1) What is your DHCP lease duration set for on these clients?
2) What is your DNS scavaging No Refresh setting set for?
3) What is your DNS scavaging Refresh period set for?

If you have questions on Dynamic DNS Scavaging please review the following article:
http://support.microsoft.com/kb/932464

Remember I said I didn't think the disappearing DNS records were related to the errors you provided? I had to look these up, because I wasn't familiar with the event ID number. Here is the article that popped up on those errors:
http://support.microsoft.com/kb/824217

You may be able to ignore these errors.

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Author Comment

by:manassehkatz
ID: 20435752
Interesting - I'll look at the DNS/DHCP settings.  I can't ignore the other errors, though, because apparently the network drive connection is lost when they happen, and they happen regularly.  As they happen regularly, and with reboots of everything, I don't think that MS article applies here.

I'll check on Monday when I get onsite and let you know.  Thanks.
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Expert Comment

by:ChiefIT
ID: 20532532
Hi Manassehkatz:

What did you come up with on the dissapearing DNS records? Was it your scavaging times?

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Author Comment

by:manassehkatz
ID: 20534021
Never found what happened.  On the three stations that had problems I just hardcoded the dns, leaving the ip address with dhcp.  No more problems.  Don't know what caused it, but this stopped it.
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Author Comment

by:manassehkatz
ID: 20686340
I'm closing this out.  After a couple of weeks, it appears that hardcoding the dns took care of it, even if I don't know what the cause was.
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Author Closing Comment

by:manassehkatz
ID: 31412449
I never really got what I wanted, but this was the closest to my actual solution.  The problem is the it was dhcping from the server - I don't know why it would drop that after some time.
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