Does DHCP server take IPs back from sleeping systems before its lease expires?

Bruce Hudson Bruce.Hudson at Dal.Ca
Fri Dec 7 16:28:40 UTC 2007

> I have a quick question here: If the IP addresses of a certain scope
> are exhausted, how does DHCP server handle new requests?

    With nothing to OFFER, it ignores the DISCOVER requests.

> In such situations, will DHCP server checks if there are any inactive
> systems, and if so, get IPs from these sleeping systems? I don't
> think this is the case. I believe if a lease is not  expired, DHCP
> server won't take the IP back for a new request, even if the IP owner
> is sleeping at current time. Is it true?

    You are correct. There is no provision in the DHCP protocol to take
a live lease away from a client. If this is an issue, the answer is to
use shorter leases.
Bruce A. Hudson				| Bruce.Hudson at Dal.CA
UCIS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405

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