Question : How to make DHCP fault-tolerant?

Hi,

I have setup a DHCP server with closed scopes. Users need to have their PC's MAC address registered in order to receive IP address and get connected to the network.

I am looking for a way to make the DHCP service fault-tolerant by setting up another DHCP server. How can I do this without putting it in a cluster? If I set up the 2nd DHCP server but do not activate the scopes, is there any 3rd party software that can do the 'fail-over'?

Thanks!

Answer : How to make DHCP fault-tolerant?

Started to look through the above but....

You don't need failover.  Traditionally you create non overlapping scopes or at least scopes that overlap but have excludes so only one server gives out each address.

If there are no dynamic addresses, only pre-determined ones then you register the mac address and associated address on both servers and run them both with the same scope.  If you need a dynamic range too then add a non-overlapping range to each DHCP server.

e.g.

Scope 1 & 2 192.168.0.10 to 192.168.0.254
Scope 1 Exclude 192.168.0.10 to 192.168.0.244
Scope 2 Exclude 192.168.0.10 to 192.168.0.234 and 244 to 254

gives 10 addresses available on each server for dynamic addresses.  use the range 10 to 234 for your reserved addresses.

The client will send out a request and get back two (in this case identical) address offers then acknowledge just one of the two (the one that replies first).  Adds a second packet to the network each time there is a DHCP request but that is neither here nor there.  The same scenario as with running redundant DHCP with two different scopes.

Also put your failover server on another site and configure WAN routers to forward the DHCP broadcasts and you have an offsite DHCP redundancy setup.

hth

Steve