Creating redundant DHCP and DNS servers

In Chapter 6, Configuring Network Services, we set up DHCP and DNS servers. This is great, but unfortunately there's one major problem. Either one is a single point of failure. If the DHCP server were to go down, new devices wouldn't be able to receive an IP address, and clients that are currently connected will drop off the network as their current IP lease expires. If the DNS server were to go down, clients wouldn't be able to reach destinations by the hostname. Depending on the scope of your network, this downtime might be hard to deal with, so having redundancy for these services may be a good idea.

With a DHCP server configured for redundancy with another server, it will synchronize its list of IP addresses that were issued, and each will detect if the other stops responding. In this case, the secondary would take over the task of issuing new IP addresses. With DNS, it's just a matter of adding another DNS server on your network, but I'll talk...