This article was previously published under Q306780
If a Windows 2000-based Dynamic Host Configuration Protocol (DHCP) server is configured to perform dynamic updates on behalf of clients, the PTR records that are created in the reverse zone are not removed when the DHCP lease expires, or when the lease is released by the client. This can cause a buildup of PTR records for a given IP address and cause a reverse lookup to generate unexpected results.
To resolve this issue, enable the Discard forward (name-to-address) lookups when lease expires option in DHCP Server or Scope properties. This causes the server to remove PTR records upon the termination of a client lease. To configure this setting for the DHCP server:
In the DHCP snap-in, right-click the DHCP server, and then click Properties.
Click the DNS tab.
Click Discard forward (name-to-address) lookups when lease expires.
You can also use this procedure on single scopes rather than in DHCP Server properties. A scope-specific setting is preferable if not all scopes are configured for dynamic updates, or if this behavior is not appropriate for all scopes.