DHCP Lease Renewals

S Carr sjcarr at gmail.com
Fri Jul 15 10:50:57 UTC 2016

On 15 July 2016 at 11:31, Bob McDonald <bmcdonaldjr at gmail.com> wrote:
> However, what happens if the client leaves the network before T1 and then
> returns before lease expiration? Does the client renew the existing lease?
> What's the sequence? (Probably clear to most, just not to me...)

It's highly dependant on the client, some will do a DHCPREQUEST
unicast to renew, others broadcast, some will start back with a
DHCPDISCOVER. However on the server side the lease is still valid and
active (server doesn't really care about T1 or T2), so the server will
give the client the IP address again and extend the lease.

> Does MCLT play into this at all? (MCLT is usually 3600 seconds, I think)

No impact (unless the DHCP servers are in communications-interrupted state).

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