Client machine knocks servers DNS OUT!

[OverDrive]

I am running a server 2003 box, and setting it up to get ready to deploy to a remote location.

Everything is working GREAT, I can log on machines, get to the net all network shares are fine, DHCP is handing out perfect and DNS is resolving greatly.

There is ONE issue however, when I plug my personal compter into the router/switch the server is on, and try to hand it a DHCP address... the DNS on the server goes NUTS and stops working.

To break it down I will give you my set up.

1 server (running 2003) on a router/switch, plugged into my cable modem.
1 client PC (running win2k) on the same router/switch

What I do is do a ping -n 1000

http://www.google.com

on the server... this gives me a "real-time" DNS monitor that I can visually see while enabling DHCP on the client machine.

Now I go over to the client machine and enable DHCP to get an address from the server... I can get an address but just as that happnes BANG, I look over to the server and I am getting request timed out... and no more access to the net until I reboot the client machine and disable DHCP.

HOW IN THE WORLD can this happen?

I should let you know that this is the ONLY client that does this... none of the others do this issue.

Any Ideas?
Chance~

 

[ChicagoTechNet]

So the switch connects the cable modem and both server and client conenct to the switch. What are the ip addresss for the both computers? or posting the results of ipconfig /all here may help.


Robert Lin, MS-MVP, MCSE & CNE
Windows, Network, Internet, VPN, Routing and How to at

http://www.ChicagoTech.net

 

[OverDrive]

Well, currently the IP of the client is in the 192 range because that is the switch's IP and I am doing this to access the internet currently. The server is in the 172 range for its host address... The server is handing out the DNS of the switch to all the clients etc...

The client machine (right now) is set up with the ip schema of the switch (192) and also has the hard set DNS in there so I am able to access the internet.

The problem is if I enable DHCP on this client (the only one mind you) is when the problem occur?

any thoughts?

Not sure how to copy all that IPconfig information from DOS.

 

[OverDrive]

I mean "router" not switch btw...

 

[mihai1]

I have a idea . The DHCP service it's not working thrue a router . The router bloks the ports 67 and 68.And DHCP it's working with 67 and 68

 

[xmsre]

Let's see if I have this straight. You have a cable modem that connects to the internet. Behind the cable modem is a router. You have two subnets off the router, 172.16.x.x and 192.168.x.x. Ther server sits on the 172 subnet, and the client is on the 192 subnet. We'll assume that all the route are correct to route from 172 to 192, 192 to 172, 172 to internet, 192 to internet, and the internet to 172 and 192. It does sound like son NATing is going on here somewhere, but you'll have to fill in the details.

Now for the client to get a lease from a DHCP server on another subnet, you have to set the ip helper-address on the router to point to the DHCP server. If it's a Cisco router, you also have to disable UDP forwarding of 138 and 139, like ip no forward-protocol UDP 138. If you don't do this, you'll have all sorts of browser issues.

 

[OverDrive]

xmsre...

Thanks for the post.

This is the way it is set up

Router IP - 192.168.1.1
Server IP - 172.18.105.4
Client IP - 192.168.1.100 (temp to get internet access)

Router - DHCP is disabled and the DNS is set to 66.86.1.20
Server - I have the forwarders going to the DNS correctly
Client - I have force set the DNS for 66.86.1.20 (temp)

Now... on ALL other computers in my network, I can log on to the domain and get to the internet and share resources, etc... no problems whatsoever, as advertised.

But this ONE client (which happens to be my personal PC) when I try to set the NIC to DHCP to register an IP from the server, it somehow knocks my DNS off the server, rendering all other clients (on the domain) including the server from access to the net until I force my PC back to static.

Strangest thing I have EVER seen?

thoughts?