Multi-server pool question.

T MANIKANDAN-PKXR74 manikandan.t at
Tue Feb 17 14:50:36 UTC 2009

The thumb rule in failover protocol as far as I know is.

1. The failover protocol allows only two DHCP server to share common IP
pool, Not more than two.
2. The Failover server and Primary DHCP server should have common
configuration (/etc/dhcpd.conf) and only varied in failover


-----Original Message-----
From: dhcp-users-bounces at
[mailto:dhcp-users-bounces at] On Behalf Of Phill
Sent: Monday, February 16, 2009 2:55 PM
To: Users of ISC DHCP
Subject: Re: Multi-server pool question.

Simon Hobson wrote:
> Phill Harvey-Smith wrote:
>> Is there a way that I can resolve this issue, bu configuring the 
>> servers to share pool information, or will I have to reserve 
>> allocation of the pool addresses to only one of the servers but let 
>> the others also manage the statically assigned ones.
> Three options come to mind :
> 2) Run two (and only two) servers as a failover pair. Both servers can

> issue addresses from the pool, but they will communicate with each 
> other to avoid conflicts. If one fails, the other can run the whole

In this case I take it that we can still have more than 3 servers as
long as only 2 of them are setup for failover, and only the failover
servers serve the pool.

This might not be an issue if I can get dhrelay going.

> Also, note that you must NOT have any statically assigned address (via

> host statement) that is also in a dynamic pool..

Yep, this is handled by the php code and the database, which has a flag
for dynamic or static, and will only write out static hosts if marked



Phill Harvey-Smith, Computer Technician, Department of Biological
Sciences, Warwick University.
Email: phill at, Phone: 024 7652 8385.
"The Days' as dark as the night is long" -- U2, Ultraviolet.
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