topic Re: XP name resolution issue in Operating System - Microsoft

XP name resolution issue

Fred Martin_1 — Thu, 18 Sep 2003 18:11:52 GMT

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 mail.applicatorssales.com [209.113.182.2]

So I do this at a cmd prompt:

C:\> ping mail.applicatorssales.com
Pinging mail.applicatorssales.com [64.94.110.11] with 32 bytes of data:
...etc...

C:> nslookup mail.applicatorssales.com
Server: ns1.applicatorssales.com
Address: 192.168.1.66

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.

Re: XP name resolution issue

Fred Martin_1 — Thu, 18 Sep 2003 18:14:11 GMT

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

C:> nslookup mail.applicatorssales.com
Server: ns1.applicatorssales.com
Address: 192.168.1.66

Name: mail.applicatorssales.com
Address: 192.168.1.68

Re: XP name resolution issue

Jon Finley — Fri, 19 Sep 2003 04:50:37 GMT

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.

http://support.microsoft.com/default.aspx?scid=kb;en-us;318803&Product=winxp

Jon

Re: XP name resolution issue

Jorge Pinto Leite — Wed, 24 Sep 2003 07:59:50 GMT

Fred, I assume you are in same lan as mail.applicatorssales.com (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!
Rgds,
Jorge

Re: XP name resolution issue

Fred Martin_1 — Wed, 24 Sep 2003 08:25:00 GMT

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.

Re: XP name resolution issue

John Collier — Thu, 25 Sep 2003 12:24:18 GMT

Fred,

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.