The DHCP configuration file can be a very useful form of documentation for the local network hardware configuration. It can be prepared in advance for new installations and updated as clients are added. Including information for all machines, including those that do not utilize DHCP, avoids accidental IP address conflicts and similar errors.
Most DHCP servers have a configuration capability that permits control of the IP address and other information provided to the client. These controls can pre-allocate a specific IP address, etc. to a machine based on the requested machine name or MAC address. These pre-allocated IP addresses then ensure that these specific machines are always assigned the same IP address. Legacy systems that do not utilize DNS can continue to use fixed tables with IP addresses when the DHCP server has pre-allocated the IP addresses for those services.