Correct Failover / DHCPOFFER functionality

[Robert Hille]

Hello all,

I've been looking through my dhcp logs to try to diagnose a problem and 
have run into something I'm curious about.

I had thought that (if configured correctly) when a pair of dhcp servers 
  were in failover  mode, each would answer the request based on 
balancing spec'ed in RFC 3074.

Both servers should see the request, but I had thought that only one 
would reply (as in send an offer) based on the load balancing.

However, I'm seeing this in my logs:

Jun 29 06:08:32 ns-dhcp-07 dhcpd: DHCPDISCOVER from 00:1d:4f:xx:xx:xx 
via 10.0.0.254
Jun 29 06:08:32 ns-dhcp-08 dhcpd: DHCPDISCOVER from 00:1d:4f:xx:xx:xx 
via 10.0.0.253
Jun 29 06:08:33 ns-dhcp-08 dhcpd: DHCPOFFER on 10.144.150.154 to 
00:1d:4f:xx:xx:xx (iPod-9) via 10.0.0.253
Jun 29 06:08:33 ns-dhcp-07 dhcpd: DHCPOFFER on 10.144.150.32 to 
00:1d:4f:xx:xx:xx (iPod-9) via 10.0.0.254
Jun 29 06:08:34 ns-dhcp-07 dhcpd: uid lease 10.144.150.32 for client 
00:1d:4f:xx:xx:xx is duplicate on shared-wireless
Jun 29 06:08:34 ns-dhcp-07 dhcpd: uid lease 10.144.150.32 for client 
00:1d:4f:xx:xx:xx is duplicate on shared-wireless
Jun 29 06:08:36 ns-dhcp-08 dhcpd: DHCPREQUEST for 10.144.150.154 
(10.136.20.4) from 00:1d:4f:xx:xx:xx (iPod-96) via 10.0.0.253
Jun 29 06:08:36 ns-dhcp-08 dhcpd: DHCPACK on 10.144.150.154 to 
00:1d:4f:xx:xx:xx (iPod-9) via 10.0.0.253
Jun 29 06:08:36 ns-dhcp-07 dhcpd: DHCPREQUEST for 10.144.150.154 
(10.136.20.4) from 00:1d:4f:xx:xx:xx via 10.0.0.253
Jun 29 06:08:36 ns-dhcp-07 dhcpd: DHCPACK on 10.144.150.154 to 
00:1d:4f:xx:xx:xx (iPod-9) via 10.0.0.253

The entire DHCPDISCOVER->DHCPOFFER->DCHPREQUEST->DHCPACK is duplicated.

This doesn't occur on all subnets, and from the reading I'm doing I'm 
beginning to wonder if it might be network related, maybe something with 
the helper addresses on the routers?

Any guidance would be helpful. Thank you,
Rchille