Server Move...

Keith Woodworth kwoody at
Sat Oct 14 21:10:19 UTC 2006

I have a question.

I just recently posted about moving and consolidating 2 dhcp servers into

Having just moved the first subnet from one old server to the new one a
question arose as I was watching the dhcpd log on the new server.

All clients by default get a 1 week lease. I changed that to 30 mins prior
to the changeover, let the lease time pass, changed the ip helper and
commented out the subnet on the old server, restarted the old dhcp server
and within about 30 seconds started to get traffic on the new server.

Now it was stated that the client would fall back to a DISCOVER when the
old dhcp server didnt reply.

As the new server is starting out with an empty lease file, it will see a
DISCOVER and pick a lease and hand it out. The problem I have just seen is
the new server pinged an address, saw that its in use (that client had not
renewed yet) and abandoned it and gave the DISOVERing client a different

I'm not sure if this is going to be a problem? Having the new server
abandon IP's like that right after a cutover? Would setting a shorter
lease time help? Or cause more problems?

I do have much larger subnets than active clients so I'm hoping that will
help too.


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