DHCP renew before half the lease time

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Oct 24 10:59:30 UTC 2006

<Staffan.Ungsgard at teliasonera.com> wrote:
>I have a device which ignores the lease time and sends out requests 
>to get its address renewed long before half the lease time has 
>The dhcp server then NAKs the request.

The server should not NAK the request. It is valid for the client to 
renew any time it wants to - it might just be that the user has 
unplugged and replugged the network cable, or it's woken from sleep, 
or ... and so the client wants to verify that it's network settings 
are still valid.

>One second before half the lease time has expired the client makes a 
>broacast request for the address, and that request is honored.
>Is this the correct behaviour - should the dhcp server NAK requests 
>coming to soon, or should I look for a solution on the problem 

You need to be looking at other reasons for the issue. Sniff the 
packets (I'm now a fan of Ethereal/Tethereal) and see what is 
actually in the exchanges.


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