Windows 2000 supports Dynamic DNS (DDNS), which enables the automatic addition of host and pointer records to clients' DNS domains and updates it as their IP addresses change.

DHCP clients support DDNS and can directly request that a DNS server (Windows 2000 or later) update their host records when the client IP address or host name changes. A DHCP server (Windows 2000 or later) can also submit requests to update both the client's host and pointer records.

A Windows 2000 DHCP server can also serve as a proxy for DHCP clients that don't support DDNS. For example, a Windows 2000 DHCP server can request updates for Windows 9x and Windows NT clients that are unable to submit DDNS requests on their own.

There are a couple of configuration steps you can take on the server side to implement DDNS. You can enable dynamic updates on a zone-by-zone basis. The types of updates allowed depend on whether the zone resides in the Active Directory.

AD-integrated zones offer the option of allowing only secured updates, which uses the ACL of the zone to determine who can perform an update. But you can only configure standard zones (those not stored in AD) for either unsecured updates or no updates at all.

To configure DDNS behavior for a zone, right-click the zone in the DNSconsole, and choose Properties. Specify the update option using the Allow Dynamic Updates drop-down list on the General tab.

* Choose No to prevent DHCP clients or servers from updating resource records in the zone.

* Choose Yes to allow DHCP clients and servers, including those outside of the domain, to perform unsecured updates to the zone's resource records.

* Choose Only Secure Updates to restrict the ability to submit updates to only the groups you specify.