DHCP (Unable to PING default gateway)

[ddog]

I am in a single domain environment with one PDC, and no BDC’s. I have a stand-alone server as my DHCP server, and it is a member of my domain.

DHCP seems to work fine most of the time but every once and a while I will get a client on 95, 98 or 2000 that can not get to the internet.

I can ping local systems, but if I ping the default gateway it times out. So I give them a static IP and every thing is peachy again. I am slowly losing all my clients to static IP’s. I am using a Cisco 2600 router for my default gateway.

Dose anyone have any suggestions????

 

[sobak]

Can you ping the workstation from the router? Something is not right. Next time this happens run winipcfg on the 95/98's or ipconfig /all on the 2000. Attempt to release and renew the IP Address and attempt the ping again. Is there a switch sitting between the router and the workstation? Next time get the ip address of the failing workstation and see if the Router see's it. If the router can see the workstation then maybe take a look to ensure you don't have something else answering DHCP requests. Strange problem when you get the information post it here would love to find out about this one.

david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*

 

[ddog]

The problem is I do not have acces to the router because it is maintained though a third party. I have released and renew the IP addresses of the client systems and it renews just fine but it will still not ping the gateway.

 

[sobak]

Going to be hard if you don't have access to the router. I've though about this for a long time and I'm sorry I just don't have the answers for this one. I asked above if there was a switch between your network and the router. I wonder if it could be an ARP cache on the switch that is causing an issue. If there is not one try clearing the arp cache on the local workstation.

arp -d * (I know this works on NT and 2000, don't know about 95/98)

and see if that works. I'm trying to think of everything I would do and I'm coming up short. Let us know if you find the problem, would be nice to know......

one other thing, could you possibly change your DHCP range to either something higher or lower in the Subnet (don't know if your using the entire network for DHCP) maybe the router is set to filter those addresses. I'm shooting in the dark here.....

david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*

 

[ddog]

We use six Cisco 2924 switches. I have been researching this problem for a while also. I have not tried to clear the workstation arp cache yet.(I will now)
I have also been told that my problems is in the router arp cache like you talked about. But as I said I do not have access to the router. We are geting ready to move our site, and that means a new router with new configuration and a new DHCP scope. So hopefully that will solve me problems.

Thanks for your help.

 

[wybnormal]

Instead of giving static ips.. just add the default gateway as static. The settting will always over ride the DHCP setting. THis way the IPs are still DHCP.

But, who is supplying the DHCP... if it's a MS server, I have seen this before. It's a MS feature.. just mark the bad address as reserved with a bogus MAC and the PC will be forced to pick up another. After a week or so, remove the stuck IP from the reserve status and delete the bogus MAC.. should be fine after that.

MikeS
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[ddog]

It is an NT server 4.0 SP6a. And that discribes my problem do you have any more information on it???

Thanks,