Dynamic Update DNS Client

Windows 2000 includes support for dynamic updates to DNS as described in RFC 2136. Every time there is an address event such as a new address or renewal, the DHCP client sends option 81 and its fully qualified domain name to the DHCP server and requests the DHCP server to register a pointer resource record (PTR RR) on its behalf. The dynamic update client registers an address resource record (A RR). This is done because only the client knows which IP addresses on the host map to that name. The DHCP server might not be able to properly complete the A RR registration because it has incomplete knowledge. However, the DHCP server can be configured to instruct the client to allow the server to register both records with the DNS. Changing registry entries changes the behavior of the dynamic update DNS client.

The Windows 2000 DHCP server handles option 81 requests as specified in RFC 2136. If a Windows 2000 DHCP client talks to a DHCP server that does not handle option 81, it registers a PTR RR on its own. The Windows 2000 DNS server is capable of handling dynamic updates.

Statically configured (non-DHCP) clients register both the A RR and the PTR RR with the DNS server themselves.

If the remote access client connects to a Windows 2000 computer running the Routing and Remote Access service, the client must perform the DNS registrations itself, because the remote access server does not know the client name. If the line goes down, the address lease expires, or the client fails to unregister its records, the remote access server will unregister the PTR record on the client's behalf.