Optimizing DHCP Through Proper Maintenance

The DHCP database is stored in the dhcp.mdb file, located in \%systemroot%\system32\dhcp. This database is structured using Microsoft JET database technology, the same technology used for Exchange Server, Active Directory, and many other databases in the Microsoft world.

As any administrator who has worked with JET databases will attest, frequent maintenance of the DHCP database is required to keep it functioning properly and to groom it for defragmentation and recovery of whitespace. By default, DHCP is configured to perform online maintenance to the database, but only during intervals in which it is not being used for client requests . For busy, large DHCP servers, there might never be downtime, so it is therefore important to run offline maintenance against the dhcp.mdb file on a quarterly to semi-annual basis.

You can run maintenance against the dhcp.mdb DHCP database file by using the jetpack utility in Windows Server 2003. From the command line, enter the following commands, illustrated in Figure 13.33, to stop the DHCP Server service, compact the database, and restart the service:

Figure 13.33. DHCP database maintenance.

• cd %systemroot%\system32\dhcp

• net stop dhcpserver

• jetpack dhcp.mdb tmp.mdb

• net start dhcpserver

BEST PRACTICE: Maintenance Schedules

A maintenance schedule for DHCP and all other Microsoft JET-based databases should be established, in addition to any other maintenance schedules that might be in effect. Such a schedule will help to keep these network service environments in top shape. Using redundant servers that will take over while the database is down can also minimize downtime from this maintenance.