DHCP gives out same IP address to two clients

[Eivind Olsen]

Hello.

I'm not sure what could be happening here, but it looks like one of our
DHCP servers for some reason decides to give out the same IP address to
two clients. The version is 4.2.5-P1.
The thing that strikes me as perhaps a bit odd is that the hardware
addresses of the two clients are _almost_ the same (one ends in "d9", the
other in "db"). That might be a coincidence, though.

Am I missing something obvious here? Or could someone point me in the
right direction? :)

Here's an example regarding one of the clients:

Jan  8 15:09:55 no-bgo001-dhcp02 dhcpd: DHCPDISCOVER from
08:76:ff:c6:43:d9 via 89.11.144.1
Jan  8 15:09:55 no-bgo001-dhcp02 dhcpd: DHCPOFFER on 90.149.65.210 to
08:76:ff:c6:43:d9 via 89.11.144.1
Jan  8 15:09:55 no-bgo001-dhcp02 dhcpd: DHCPREQUEST for 90.149.65.210
(80.202.6.108) from 08:76:ff:c6:43:d9 via 89.11.144.1
Jan  8 15:09:55 no-bgo001-dhcp02 dhcpd: DHCPACK on 90.149.65.210 to
08:76:ff:c6:43:d9 via 89.11.144.1
Jan  8 17:09:55 no-bgo001-dhcp02 dhcpd: DHCPREQUEST for 90.149.65.210 from
08:76:ff:c6:43:d9 via eth0
Jan  8 17:09:55 no-bgo001-dhcp02 dhcpd: DHCPACK on 90.149.65.210 to
08:76:ff:c6:43:d9 via eth0
Jan  8 19:09:55 no-bgo001-dhcp02 dhcpd: DHCPREQUEST for 90.149.65.210 from
08:76:ff:c6:43:d9 via eth0
Jan  8 19:09:55 no-bgo001-dhcp02 dhcpd: DHCPACK on 90.149.65.210 to
08:76:ff:c6:43:d9 via eth0

Here's an example from the other client:

Jan  8 17:11:43 no-bgo001-dhcp02 dhcpd: DHCPDISCOVER from
08:76:ff:c6:43:db via 89.11.144.1
Jan  8 17:11:43 no-bgo001-dhcp02 dhcpd: DHCPOFFER on 90.149.65.210 to
08:76:ff:c6:43:db via 89.11.144.1
Jan  8 17:11:43 no-bgo001-dhcp02 dhcpd: DHCPREQUEST for 90.149.65.210
(80.202.6.108) from 08:76:ff:c6:43:db via 89.11.144.1
Jan  8 17:11:43 no-bgo001-dhcp02 dhcpd: DHCPACK on 90.149.65.210 to
08:76:ff:c6:43:db via 89.11.144.1

Here's information taken from the dhcpd.leases file. It looks to me like
the starts/ends are overlapping.

lease 90.149.65.210 {
  starts 3 2014/01/08 16:09:55;
  ends 3 2014/01/08 20:09:55;
  cltt 3 2014/01/08 16:09:55;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 08:76:ff:c6:43:d9;
  uid "589br";
  option agent.circuit-id "DSA03ANR eth redacted";
  option agent.remote-id "redacted";
}

lease 90.149.65.210 {
  starts 3 2014/01/08 16:24:02;
  ends 3 2014/01/08 20:24:02;
  cltt 3 2014/01/08 16:24:02;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 08:76:ff:c6:43:db;
  uid "589br";
  option agent.circuit-id "DSA02KVST eth redacted";
  option agent.remote-id "redacted";
}

Regards
Eivind Olsen