Urgent DHCP problem

[Zucarita9000]

The setup is pretty simple, a bunch of clients connected to a Small Business Server 2003, acting as the DHCP server.

Everything was working ok on friday, but this morning, some users couldn't log on to the network, as they didn't get an IP address from the server.

After checking and re-checking, I noticed that tha server was no longer giving IP addresses. I restarted the service, but the problem persits.

What can be wrong here?

 

[Skunk]

Ensure that the scope is still active and still authorized by Active Directory. Then you can go from there troubleshooting connectivty (ie the server still has a valid address and can contact any switches etc.)

 

[RebateMonger]

You need to check the Event Logs and the Services list and see what happened, and which Services are dead. Your post implies that the DHCP Service has stopped? If so, you need to check out its dependencies and see what other Services it's dependent on.

If DHCP is totally messed up, you can always delete the whole Scope and re-create a new scope. You may have to delete the databases associated with the Service.

 

[Cooky]

yes, check EventLogs first. Look for an error that indicates the box is not authorized to serve DHCP.
If such an error doesn't exist, move on to next step.

If the box also provides VPN connectivity, check your Routing and Remote Access setting and ensure it didn't grab all the DHCP IP's. Usually you want to assign static scope for VPN instead of DHCP unless you're very clear what you're doing.

 

[petey117]

and check your active leases vs remaining leases. you could be out of IP addresses (especially if you have wireless, and people are leeching your connection)

 

[Zucarita9000]

Well, the scope is still active and authorized. There are plenty of IP addresses left (around 200), so that shouldn't be the problem. The service is running just fine.

I'll post again tomorrow if the problem persists. It got messed up by itself, so maybe it'll fix itself too.

 

[Zucarita9000]

Well, the problem did not fix itslef, so I was thinking about getting rid of the DHCP server. Since we have only abou 12 clients, I figured I can manage static IPs.

The server is not asigning IP addresses for some reason. Those users who still have a valid lease do get their IPs whenever they logon, but on the 14th most of those addresses will expire and the server will not give them new ones. Isn't that weird?

 

[nweaver]

Time to go old school...

bust out that old hub (if you are a geek, you have at least one in the closet) and fire up ethereal. You should see DHCP discovers/Requests from the client, and DHCP offers from the server. Check the offer, make sure it's well formed (contains all elements)

either take a tcpdump and open offline, or do this on a box that you don't care if it dies. Ethereal is like swiss cheese security...

 

[RebateMonger]

Static IPs suck. They get misconfigured, people can't network, people get identical IPs, you can't maintain DNS...and so on. DHCP is SO easy to maintain. And it makes DNS maintenance automatic, too. Effortless..... (except if it breaks, of course )

If the Server says that everything is fine, then it may be a NIC, cable, or switch problem. Hook a known-good laptop directly to the server with a known-good cable and see if it gets an IP address. You can use Network Monitor on the Server side to watch DHCP request/response cycles and see if they are behaving normally.

 

[petey117]

also, run a netdiag on the server and post the results here