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Operating System - Microsoft
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XP name resolution issue

Fred Martin_1
Valued Contributor

XP name resolution issue

I mentioned this in another thread some time ago but got little response. On all of my XP machines, sometimes I get the following:

A user's mail client will complain that it can't reach our mail server:

Could not connect to []

So I do this at a cmd prompt:

C:\> ping
Pinging [] with 32 bytes of data:

C:> nslookup

How can three tools all resolve to different addresses? In particular ping and nslookup, what the heck is up with that?

Note the DNS server is not at fault. All of my unix, WinME, WinNT and Win98 clients resolve just fine.

This is only happening on all my XP machines.
Fred Martin_1
Valued Contributor

Re: XP name resolution issue

Sorry my nslookup example is incomplete. It looked like this:

C:> nslookup

Jon Finley
Honored Contributor

Re: XP name resolution issue

Part of the difference is caused by DNS caching Win2000, XP and 2003 only.

This "feature" can be turned off, and "may" resolve part of your problem.;en-us;318803&Product=winxp

"Do or do not. There is no try!" - Yoda
Jorge Pinto Leite
Respected Contributor

Re: XP name resolution issue

Fred, I assume you are in same lan as (even if this server is in a DMZ zone), isn't it?
That can explain why you are getting different IP address to different command lines.
I don't know how XP handles this situation. But my guess is for you to look into firewall and routing for all XP's machines.
Keep us updated!
Fred Martin_1
Valued Contributor

Re: XP name resolution issue

Same LAN. It's a simple situation really. All are static IPs, one segment, one network. I'm running DNS on a unix box here. All PCs have my DNS server as primary and my ISP's DNS server as secondary. My DNS server forwards to my ISP when needed.

Now, if a DNS lookup for mail comes back with the -public- IP address, it's because my DNS server isn't responding. The request is forwarded to my ISP, either by my DNS server or by the host itself, and my ISP resolves the name to the public IP.

However, it sometimes returns a completely odd address, which I can't see any connection to.

I get trapped into thinking that DNS servers are the issue when I know that my other hosts all resolve fine.

Seems like it's got to be an XP thing. There are user DNS settings in XP that are not available in ME,95,98 ... maybe it's one of those?

For nslookup and ping to come back with two different addresses in the same shell on the same XP host, it's obvious that they are not both following the same rules.

Anyway it's taking a lot of time to resolve, since it happens infrequently. I only get to test settings changes now and then, and I won't know about success until many weeks go by without the problem showing up.
John Collier
Esteemed Contributor

Re: XP name resolution issue


I know this isn't the most desirable way to solve such an issue, but you could always go in and clean all of the stored DNS entries in each XP machine with the command 'ipconfig /flushdns' and then put an entry into the host file for each of the machines that are having the problems when it comes to resolving the proper IP address for this mail server.

Since you are using all static IPs on your LAN, this may be the most simple resolution to the situation in the long run.

Believe it or not, M$ still parses the Host file prior to searching the DNS.
"I expect to pass through this world but once. Any good, therefore, that I can do, or any kindness that I can show to any human being, let me do it now. Let me not defer or neglect it, for I shall not pass this way again." Stephen Krebbet, 1793-1855