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Exchange Server name resolution associated with DHCP lease renewal

Posted on 2004-09-16
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Last Modified: 2008-03-10
Running Win2k Server (Basic) and active directory in native mode.  I have a problem with approximately 4 client computers during IP lease renewal.  When a user starts the client and logs onto the network, all shared resources/printers are just fine.  What isn't fine is when the user tries to start Outlook 2000.  Outlook 2000 cannot seem to locate the exchange server.  When I run a tracert to the exchange server, the route comes back to our gateway's external IP address - not the internal IP address.  Same with ping, it will ping the external IP of the gateway, but not the internal IP of the exchange server.

What happens is the user is presented with a logon pop-up box that asks for username, password, and domain.  Nothing works no matter what is input.

This is only happening with approximately 4 clients (the same 4) out of a network containing 100 computers in the domain.  What's frustrating is that the problem seems to self-correct in 5 to 10 minutes.  After about 5 to 10 minutes the client will be able to properly tracert the exchange server to the internal IP and pinging the exchange server will ping the proper internal IP.

The problem appears randomly, but seems most prevalent at lease renewal from the DHCP.  I've created a batch file to capture the ipconfig information and dns cached information for the client the next time this happens to hopefully further track down the cause.

All other clients on the network do not experience this issue and I can't figure out what is different or needs fixed.
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Question by:kalittaair
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Expert Comment

by:rhandels
ID: 12079481
Hi,

Make sure the internal NIC of the Exchange server has priority over the external (go to Start --> Option --> Network Dial Up connections. Then, go to Advanced and Advanced Options, this might be the problem..
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Expert Comment

by:rhettlee
ID: 12081717
Well its definitely a DNS problem but if it only appears on 4 clients and they are not mobile clients then the quickest way to solve this is just manually define the IP address of your exchange server on the HOST file of those 4 clients.

I've encountered this problem to but haven't found the real solution so i just did the work around.

HOpe this helps.

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Author Comment

by:kalittaair
ID: 12084159
rhandels, thanks for the input.  The Exchange server does indeed have 2 NICs installed, however one of them has been disabled since the server only needs one.  It's only there as a backup NIC.

rhettle, I'm glad to see that we're not the only IT department to see this issue.  We considered adding HOST files on the 4 clients, but would only do that as a last resort.  We really don't want to get into haveing to remember to change host files on specific clients should we make changes in the future.

Right now, we are to the point of completely blowing away these 4 clients and reinstalling the OS to see if it corrects the problem.  I'd put that as next to last resort with HOST files as last resort.  Still looking for a better solution.
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adamdrayer earned 500 total points
ID: 12084864
what DNS servers is DHCP issuing?  Just internal DNS?  or an external DNS server as well?
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Author Comment

by:kalittaair
ID: 12085326
DHCP option 006 DNS Servers:

192.168.1.2 Internal Primary (same DNS info as 192.168.1.3)
192.168.1.3 Internal Secondary (same DNS info as 192.168.1.2)
198.6.1.3 External
198.6.1.4 External
193.6.1.5 External
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Author Comment

by:kalittaair
ID: 12085337
last is a typo: 198.6.1.5
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by:adamdrayer
ID: 12085739
>> Same with ping, it will ping the external IP of the gateway, but not the internal IP of the exchange server.

You can't ping the internal IP address of your exchange server?  are these computers on the same subnet?  do you have the exchange server address reserved in DHCP?

Check the clients "NetBIOS over TCP/IP" settings on the WINS tab of network properties.  Compare these machines to the rest.

What do you think about configuring DHCP to only issue internal DNS servers?  
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by:crissand
ID: 12086242
I found this behaviour when user has expired password. The system has asked him to change it, but the user ignored the warning. Also this was hapened on Windows 98 computers running Outlook 2000 when the domain controller was on a slow connection line. I also found this behaviour related wto wins server rather than the dns server, but restarting wins service solved that.

What is the result of ipconfig /all run on one of the problems machine?
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Author Comment

by:kalittaair
ID: 12086383
Let me clarify.  If I ping the Exchange Server NAME or do a tracert to the Exchange server NAME from the client, it will resolve the Exchange Server's name to our external IP address of our gateway (not the Exchange server's proper IP address - which is internal with only one NIC -- the Exchange server does not have an external IP or external NIC).  If I ping the Exchange server's internal IP address specifically (NO NAME), there is no problem with ping or tracert.  It appears to be a name resolution issue somehow with these clients.

All computers are on the same subnet.  The exchange server's IP is statically set and its IP address is excluded from distribution by DHCP.  Since the Exchange server is on a static and excluded IP address, there's no need to reserve it, correct?

If I set DHCP to issue only the internal DNS servers, how would a client know how to resolve names not on my internal DNS (i.e. www.msn.com)?

Currently, our user passwords do not expire (working on implementing a program to fix that).  The clients are all Win2k.  We also run WINS server, due to 2 or 3 remaining Win98 clients on the network.  But I don't understand how that would affect the Win2k machines.  Could you clarify?

Ipconfig /all looks normal on the machines when the problem is encountered.
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by:adamdrayer
ID: 12086425
>>Ipconfig /all looks normal on the machines when the problem is encountered.
Including "Node Type"?

>>If I set DHCP to issue only the internal DNS servers, how would a client know how to resolve names not on my internal DNS (i.e. www.msn.com)?

In the server properites in the DNS MMC, you can enable Forwarding.  All clients would request DNS resolution from your internal server, and if your internal server cannot accomodate them, it forwards the request to external DNS servers.  I prefer this at all times over mixed internal/external DNS servers.  
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Author Comment

by:kalittaair
ID: 12087996
Node type on all machines is Hybrid (same as the clients with no problems).

I see what you're saying with DNS, but I can't see that being the problem with these 4 clients connecting to the Exchange Server.

It did happen again this afternoon, but self corrected before I could get to it.  Yesterday I did write a batch file to get the IPCONFIG /all and IPCONFIG /showdns, but the user didn't run it because their manager didn't brief them to do it when the machine experiences the problem.  I'm still hoping to get the ipconfig information during an event.
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by:Sembee
ID: 12088354
Loose the external DNS servers from DHCP. AD clients should be using ONLY AD servers for DNS. No others. Similarly the servers should be looking at the domain controllers for DNS ONLY. There should be no external DNS servers anywhere in the network configuration.

Windows 200x server is quite capable of looking up DNS information off the internet on its own - but if you are having problems then use forwarders - but that is the ONLY place external DNS servers go in the network config.

Simon.
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by:crissand
ID: 12088511
I asked about the ipconfig results because it's not usual to have pointers to external dns server since you run your own dns which can forward requestst to the external dns. And I want to see the default gateway and the network mask.
Maybe running ipconfig on one good machine will help us.

But now I think the problem is in the 5 dns. "Announce" to workstations, using dhcp, only the internal dns servers addresses and configure each internal dns server to do forward requests to the external dns.

I think I wrote the same advices as sembee...
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Author Comment

by:kalittaair
ID: 12101432
Okay, have removed the external DNS addresses from being served out by DHCP.  Will now wait to see if the problem reoccurs.  Also have to wait to see if the night IT re-installed the OS on those 4 clients.  If no further problems, will award to adamdrayer for first suggesting removing the external DNS from DHCP.
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Author Comment

by:kalittaair
ID: 12172691
It's been over a week and I've heard no further complaints.  Keeping my fingers crossed that the DNS cleanup resolved the problem.  Thanks everyone for your help.
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