Re: Disappearing DNS

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Hi, thanks for your response. I solved the problem in the end yesterday. I had tested for other DHCP servers but got no response.I used Microsoft's latest network monitor and discovered that the OSX server we use for testing had, according to the Apple guys, turned on its DHCP server after an update. This DHCP server was not configured but for some reason the XP clients would accept the blank DNS settings from this server even though they would get the correct settings from the Windows 2003 server. I am not sure why but the XP clients seem to try to renew these DNS settings every minute instead of the usual time periods for a DHCP lease.




"grep" <grep@xxxxxxxxxxxxx> wrote in message news:#VULZ7roHHA.208@xxxxxxxxxxxxxxxxxxxxxxx
I dunno - my first thought was rogue dhcp server too. Turn it off on your server, and run tcpdump on one of your machines to monitor traffic for ports 67 and 68. If you see dhcp requests, and then see dhcp replies, you'll know you have a problem.

Another thing you could check is the IP address of the dhcp server when you're having the problem. Look at ipconfig /all for that information. If it's not what you expected, you'll know where to go.

grep

Paul wrote:
Hi, at first I thought it could be another DHCP server but it was giving out all the correct IP settings. I also disabled the DHCP server to see if anything else answered the request. I don't think the network monitor will help as the client receives the correct DNS settings but they then disappear completely - a /renew gets them back.

"Yann" <Yann@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:BBB4A66D-6859-43AB-9F18-8B1942DAFB7E@xxxxxxxxxxxxxxxx

What about a rogue DHCP server that would send incorrect informations? I
doubt it because you said the renewal time is 2 days.

Have you tried to use Microsoft Network Monitor on your XP clients and
filter on DHCP to see what could be wrong?

"Paul" wrote:

2 days

"Joshua Bolton" <JoshuaBolton@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:28F16A83-1780-41C4-8DF3-458B9867467A@xxxxxxxxxxxxxxxx
> What is the dhcp lease renewal interval set to?
>
> "Paul" wrote:
>
>> Hi, I have a weird problem. This morning some of our clients were >> having
>> problems accessing the internet. I investigated and found that
they >> had
>> lost
>> there DNS settings which were assigned by a 2003 DHCP server. I
did an
>> ipconfig/renew and they came back again.........but not for long!
Some
>> clients seems to work ok now but there is still a number which
only >> hold
>> onto there DNS settings for approx 20 - 40 minutes. They do not lose
>> their
>> own IP, WINS or gateway though. As a temporary workaround I have
added
>> the
>> DNS server entries into there network connection. I have put
procmon >> on a
>> machine and told it to filter on
>>
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\
>> to see if I can find what is accessing the reg key but so far the >> machine
>> has been ok - typical!
>>
>> FYI the servers and clients have been rebooted recently after
putting >> the
>> latest windows updates on.
>>
>> Any ideas?
>>
>>
>>
>>
.

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