Should Both Servers in a Failover Pair Log All DHCPDISCOVERs?

Austin Gabel agabel at
Thu Aug 20 13:40:33 UTC 2009

On Tue, Aug 18, 2009 at 1:58 PM, Martin McCormick <martin at
> wrote:

> We are suspecting that our failover pair may be out of sync on
> one of our wireless networks. Should both servers always log the
> DHCPDISCOVER packet from the same host even though only one will
> offer or has offered a lease?

This is normal.  Both servers should receive a request but only one should

>        We started noticing that clients in a wireless network
> were randomly getting 30-minute leases instead of the full lease
> time we had specified.

What is your full lease time that you have specified?  If you have it set to
one hour
then the clients will attempt to renew their addresses after around 30

> I began looking at the DHCPDISCOVER
> requests from a test system and noticed that there was one from
> the network in question in the syslog from the secondary DHCP
> server and never one from that network in the primary server.

This may depend on your relay agents and what server they send the requests

> Also, if one viewed /var/db/dhcpd.leases in the secondary
> server, the lease it was using was there. On the primary box,
> the last occurrence of that same address was an older lease that
> belonged to another client.

>        Is there one thing in particular that is a dead giveaway
> that the DHCP servers are not seeing the same world?

At the top of the leases file it should tell you the state of the failover

>        Thank you.
> Martin McCormick WB5AGZ  Stillwater, OK
> Systems Engineer
> OSU Information Technology Department Telecommunications Services Group
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at
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