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DHCP Leases are set for 24 hours but the clients Renew every 1 hour

we are running 45+ workstations and 4 win2k servers, our domain controller is also our DHCP Server and the renew times set on the Leases is 24 hours, however the workstations keep renewing the lease every hour.

have already tried deleting the entry in the lease  pool, using ipconfig /release /renew.


we also have about 45 ip addresses free so i know that is not the problem.

what could be causing this??
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jdonaghe
Asked:
jdonaghe
1 Solution
 
Jay_Jay70Commented:
Hi jdonaghe,

is this on all machines? are there any errors logged, have you got DHCP on a router enabled somewhere? make sure to disable it on the router if it is enabled
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carl_legereCommented:
go to a client, from a command prompt do: ipconfig /all
you will see the IP of the DHCP server and the lease information,  does it really say it is renewing every hour?
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pseudocyberCommented:
>>what could be causing this??

Old TCP/IP stacks, bugs, user manipulated registry type entries.

What are your clients?  How do you know they're renewing every hour?  Have you done a packet capture and seen the renewal request?  Can you take one machine and analyze it - what is the OS, what version, what patch level, etc.
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jdonagheAuthor Commented:
This is starting to happen on all machines, there is no error log created.

All of our workstations are running win2k pro sp4 version 5.00.2195.

When we type ipconfig /all it states that the lease will expire in 1 hour, despite the lease time period change on the server.  

DHCP is not enabled on any of our routers, the only DHCP is the server.
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pseudocyberCommented:
You could have a rogue DHCP server - like a Linksys router.  You might try disabling the interface the dhcp server is on, and then trying a release renew and see if there's a response - if so, then you've got a rogue.
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pseudocyberCommented:
Another thing - go to the dhcp server and the client.  Release the IP and renew - then on the dhcp server, do you see the correct client and MAC address leased to the correct IP?  If not, this would also indicate a rogue.
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jdonagheAuthor Commented:
Yes the IP Address is leased to the correct client.
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pseudocyberCommented:
Huh.  

Just to nail it down, I would put a sniffer capable of two way traffic - either with port spanning/mirroring or a hub in front of the DHCP server - you could filter for your test host IP and watch the request come in and how the server responds.  You would be able to see into the DHCP reply and see if the server is giving that lease period out - or if the client is doing it.  Then you can troubleshoot the source - possibly with driver updates, patches, etc.
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jdonagheAuthor Commented:
kk will try thank you
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