Should Both Servers in a Failover Pair Log All DHCPDISCOVERs?

Martin McCormick martin at
Tue Aug 18 18:58:08 UTC 2009

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?

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

	Thank you.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Telecommunications Services Group

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