DHCP Wizards? Waaaaay too many leases

[Mada_Milty]

Good Day,

I have a Win 2K3 Server running AD. I keep getting error number 1020 in the event logs. Its says that our address pool is 82% full. While they only have a scope of 51 addresses, there's NO WAY that that many addresses should be in use. There are a total of 9 computers in this company! They're using 41 addresses!

I've already read this KB (http://support.microsoft.com/kb/261964/en-us), and verified that their lease period is 8 days. No problem there. Apart from this, I don't know where to begin troubleshooting the problem. Any ideas?

[pari22]

Are you by any chance using wireless router?

[jconstan]

I'm assuming that the W2K3 server is the DHCP server?

Go to each machine on your network, there are only 9, and record the IP addresses. Usually, the DHCP server will try to issue the same IP address to the same machine after the lease runs out. Then ping the addresses that are leased but are not one of the 9. If they answer, then they are devices issuing DHCP requests from somewhere.

Or, make the pool only 9 long.....then see what happens.

Those DHCP requests are coming from somewhere.

[pari22]

If you look at the DHCP's lease list, you don't need to go to any "machines".
It will list all the leased IP's, DNS names, and mac's.
See any names that are not supposed to be there? If you have RAS turned on, check the DHCP settings for that.
If you have TS turned on, everytime you connect, it gives itself an IP. Don't know why.
Refresh and delete any unneeded IP's from dhcp lease section.

[Mada_Milty]

Thanks for all the advice.

There are no wireless routers on the network. (And if there were, they would be secure, if that's what you're getting at, pari22 ;) )

RAS is not setup.

Terminal Services is not set up on this server, but the users at this company use RDC to connect to a terminal server here. I can't imagine how that would be using addresses on their side though.

Also, there are only 5 entries in the address leases!


Ahhhh! I figured out a simple resolution as I was writing this! Probably not a permanent fix, but its freed up the erroneous leases. What I did was reconcile the address pool. It's cleared up everything! Woo hoo!

Well, that's handy. I'm convinced that the root problem is from a misconfigured lease expiration and scavenge time. I'll be playing with those over the next few weeks, and see how she goes.

Thanks again!