Duplicate DHCPACK from a failover pair

[Abu Abdulla alhanbali]

Hi,

I am running the server 4.1.1 with failover configured. The clients
receive DHCPACK from both servers. this causes the client to reboot in
many cases since it might first receive DHCPACK from a different
server than the one specified in the DHCPRERQUEST 'server identifier'
field.

The scenario is as follow:
- The client is broadcasting DHCPDISCOVER
- Both servers send DHCPOFFER
- The client choose one of them (the first one it receives) and
broadcast DHCPREQUEST including the server that it chooses in the
'server identifier'
- Both servers send DHCPACK which causes the client to reboot if it
receives the first DHCPACK from the wrong server.

My questions:

- Is it as per the RFC that both servers can respond with DHCPACK. Is
this what they call ‘lazy’ update. Can we disable it.
- In RFC 2131 (Figure 3) it shows that one server (should/can?)
respond. What is the difference between this and the failover draft
12. Should the client implement different DHCP firmware based on the
current DHCP setup (using for example a couple of standalone DHCP
servers or a failover pair).