What about BootP?

BootP, which stands for Bootstrap Protocol, is an Internet protocol that enables diskless workstations to boot themselves over the Internet. Like DHCP, BootP allows a computer to receive an IP address assigned from a server. However, unlike DHCP, BootP also enables the computer to download a boot image file, which the computer can then use to boot itself from. A significant difference between BootP and DHCP is that BootP comes into play before the computer actually loads an operating system. In contrast, DHCP is used after an operating system has been loaded, during the configuration of network devices.

Most DHCP servers can also support the BootP protocol. So if your network has diskless workstations, you can use the DHCP server's BootP support to boot those computers. At one time, diskless workstations were all the rage because network administrators thought they'd be easier to manage. Users hated them, however. So most diskless workstations are now beehives, and the BootP protocol isn't used much.

How long to lease?

One of the most important decisions that you'll make when you configure a DHCP server is the length of time to specify for the lease duration. The default value is eight days, which is appropriate in many cases. However, you may encounter situations in which a longer or shorter interval may be appropriate:

• The more stable your network, the longer the lease duration can safely exist. If you only periodically add new computers to the network or replace existing computers, you can safely increase the lease duration past eight days.
• The more volatile the network, the shorter the lease duration should be. For example, a wireless network in a university library is used by students who bring their laptop computers into the library to work for a few hours at a time. For this network, a duration such as one hour may be appropriate.

Remember Don't configure your network to allow infinite duration leases. Some administrators feel that this cuts down the workload for the DHCP server on stable networks. However, no network is permanently stable. Whenever you find a DHCP server that's configured with infinite leases, look at the active leases. You'll find IP leases assigned to computers that no longer exist.