advice on moving dhcp server

Simon Hobson dhcp1 at
Mon Dec 11 23:56:48 UTC 2006

Jeff A. Earickson wrote:

>I need to move my DHCP service from one machine to another;
>however I use the primary/failover setup with DHCP 3.0.5.
>The half that I need to move is the primary, the secondary
>stays put.

Since you are using failover, it becomes slightly easier and can be 
done with almost no break in service.

Optionally, add the new IP address to your DHCP Relay config(s)

Shut down the dhcp service on the retiring machine, and set the 
secondary to partner down.

Transfer all the settings, configs etc to the new host. You don't 
need the leases file.

Stop the service on the secondary and change the config for the 
change of IP for it's partner. You can change the config then 
stop/start the service for minimal downtime.

Start the service on the new primary - it will get the leases from 
the secondary and they will go into normal operations.

Remove the old address from the DHCP Relay configs, and add the new 
one if you didn't do it earlier.

Some clients will initially attempt to contact the old server for 
renewals, but as it won't answer they will time out and broadcast for 
a server. At that point everything will sort itself out as they get a 
lease from one of the servers - and it should be the same address as 
the old one I think.

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