General discussion


DHCP Address Leases gets 100% full

By rbautista ·
We use a Windows 2000 DHCP server and 2 of our subnets gets full in a matter of hours and the funny thing about it there was no host and the unique ID has a about 30 or more digits. We have to manually delete them so the IP addresses would be available again. Does anyone over here have the same problem? Is this a worm crawling in to our network? We tried fixing, rebuilding, restarting our DHCP servers but to no avail. Please help.Please help.

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Hotfixes and patches

by BFilmFan In reply to DHCP Address Leases gets ...

Have you downloaded all the latest patches and hot fixes for those DHCP servers?

What happens if you make a DHCP reservation for a client on that subnet?

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DHCP issues

by rbautista In reply to Hotfixes and patches

All patches are installed and if we use reservation it works fine but we still getting those IP's with no host names and long unique ID's.

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Curious Behavior

by Roger99a In reply to DHCP issues

Are those IP's active? Can you ping them?

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by cptato In reply to Curious Behavior

Tried adding a new pool?

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Sounds like a routing/traffic problem. . .

by bkinsey In reply to DHCP Address Leases gets ...

Possible explanation is extraneous traffic getting onto your network from somewhere, including DHCP request packets. Probably not fully routed, if the leases are not completing, but requests are broadcast, and could still take up leases even if name resolution can't be made.

We had a similar situation with a wireless link to a partner organization. Networks were separate, but there was no router of any kind between them, so their traffic was hitting a common switch with ours. Their machines were hitting our DHCP server, which was handing out leases as happy as could be.

That was an easy fix, as the link had just been put in, and had simply been plugged improperly. In your case, if no architectural or routing changes have taken place recently, you might need to resort to traffic sniffing to see if you can isolate where the DHCP traffic is coming from. (If that's even what's happening; as I said, it's a possibility, and seems like one of the more likely ones to me, but it could be something else.)

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Ever find the cause - we are having the same problem

by mary.christopher In reply to DHCP Address Leases gets ...

Did you ever find out what was causing the scope to max out? We have several scopes and only one of them has this problem where it maxes out. The other scopes have a few here and there, but nothing major. We basically have to reconcile every morning to free up addresses.

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possible cause

by ejdrury In reply to Ever find the cause - we ...

We are having the same problem - our network guy said that it happens sometimes if there is a machine out there using RAS.

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Solution: dhcp pool full.

by raghu In reply to possible cause

First of all, using some front end, find out who is consuming those ip addresses ? Is it a single machine or multiple machines ?

Then Isoalte those machines and scan for network worms like blackmal.

Put a script such that if any mac address renews more than the specified times, it should be blocked.

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