Strange DHCP/DNS Issues

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Gawd
Joined
Feb 4, 2004
Messages
649
Lately, evernow and again we'll recieve a call from a user who is having connectivity issues. Upon further inspection, we find that they are simply unable to resolve hostnames both localy and externaly. They can always ping IP addresses and recieve valid ip/dns/gateway addresses. All it takes is a simple release/renew to fix the problem but it can be a handful to deal with when we have other problems/projects. What could be causing this? It almost always happens after a reboot but not always.
 
When you find it, let me know. I think we had some luck locking both the switch port to 100/full (or whatever) and doing the same to the client machine's NIC if the drivers supported it. Real odd.

I tend to see lots of attempts against my firewall's inside address from 169.254.x.x when it happens.

This is my personal theory, nothing but experience to back it up:

I believe the way 2000 works (probably XP as well) is that it boots and to be more secure, does not init the NIC card until the OS is secured. Then it has a low timeout value due to the switch not negotiating fast enough. It times out and silently uses the bogus 169.254.x.x address.
 
I don't believe that's the problem. The clients are getting valid addresses that are completely within scope. They even recieve valid DNS and Gateway addresses. It seesm as though the problem is that every now and then the address doesn't get dynamically updated in DNS. This hasn't always happened. It seems to have started about a week ago when we had a short power outage. Now hardware seems to have been physically damaged however.
 
Before you renew the IP, does the proper DNS suffex show? I have had some issues on 2000 where after a reboot the DNS suffex doesn't show until I renew the IP. You may want to manually add that in the IP config and see if that helps.
 
Do you have more than one scope? Is he hitting a scope that doesn't have the proper DNS Suffix's entered?
 
I would try setting the NIc speed/duplex manually. i have seen some switch cause problem because of nigotaions failing. Also it seems like you saying it works for a while then stops? try for updated NIC drive while you at it.
 
Originally posted by TrueBuckeye
Before you renew the IP, does the proper DNS suffex show? I have had some issues on 2000 where after a reboot the DNS suffex doesn't show until I renew the IP. You may want to manually add that in the IP config and see if that helps.
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I haven't thought to check that yet. Hopefully, the next time it happens I will be able to check the client machine for that problem.

typhoon, we only have one scope (x.x.128.0-x.x.255.254).
 
Yes I do. I have even turned off the secure feature so that all dynamic updates are supported.
 
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