DHCP Redundancy

sthaug at nethelp.no sthaug at nethelp.no
Sat Nov 27 18:26:26 UTC 2010

> > If you run two servers on a network, then you must do one of two things :
> >
> > 1) Run them as a failover pair so they can manage one set of client
> > addresses between them.
> >
> > or
> >
> > 2) Run them with separate and non-overlapping address ranges so that they
> > don't interfere with each other.
> We did that on our campus, and it didn't seem to work.  The one
> time we ran out of disk space on one of the DHCP servers, we just
> had machines start losing their leases & needing to be rebooted.

DHCP depends on having enough disk space for the leases file. If you
run out of disk space all bets are off.

> It's also a giant mess to maintain -- as any static assignments have
> to be put in the config files on both machines.

Depends on your requirements, I guess. I work for an ISP, we use DHCP
with failover. All address assignments are dynamic, and we only have
the occasional pool that needs to be updated on both servers in the
failover pair.

DHCP failover seems to work well for us.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no

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