Is there some method to have multiple ISC dhcp servers on different subnets and only one backup (failover) server for all of them? How can in accomplish this task?
thank you in advance
It would be far simpler to have one active-passive pair of DHCP servers to serve all of your subnets. You would need to configure your routers to pass DHCP requests from those subnets to the pair of servers. If you have Cisco gear,
The design you propose should be achievable with ISC DHCP (use multiple failover peers on the secondary server), but you'd still need support from your routers to forward DHCP packets from the subnets to your backup server. You could instead set up the backup server with interfaces on all the subnets, but that architecture will not scale well and is less elegant.