DHCP failover - lease time it's always MCLT

John Wobus jw354 at cornell.edu
Wed Jul 1 16:04:29 UTC 2015

My understanding is the beginning of a lease is restricted to the MCLT
to give the two servers time to synch their lease info.

Have you verified that synching is happening?  If it were my problem,
to be sure, I'd check the logs and the leases files and find leases
that both servers could only know about if they're synching  
Both being in NORMAL state tells you synching is happening, but
it's something that can be easily checked.

I'd also verify that renewals look normal, i.e., with a unicast
request and ack and at the expected time.  (Not that I know if
the server acts differently when clients fall back to broadcasts
and/or discovers.)

There are other details to verify: that you know what
the client is requesting and what the server is configured to allow
as the maximum lease for the IP address in question.

John Wobus
Cornell University IT

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