In the past (and currently with most DNS servers), for a client computer to have a resource record added into a zone, the administrator for the DNS server had to manually add the record to the appropriate zone. With most networks, a DHCP server provides client computers on a network with an IP address that is leased for a given time. If DNS is the main name resolution mechanism for the network, the client computers must have resource records that are current in the DNS database so other computers on the network can locate them.
To lower the amount of work required keeping zone information current, the dynamic update protocol was introduced into the RFC standards track. The dynamic update protocol allows client computers to register resource records in their zone. The Windows 2000 DHCP service can also be configured to update the DNS zone on behalf of the client.
Windows 2000 Clients
Currently, the only resolver in the Windows suite of operating system products that has the capability to send update information to a Windows 2000 DNS server is Windows 2000. Figure 3.8 shows a Windows 2000 client updating the DNS zone after receiving an IP address from a DHCP server. The DHCP client/server configurations determine whether the client or server will be responsible for updating the DNS server information.
Figure 3.8 A Windows 2000 client updating the DNS zone after receiving an IP address from a DHCP server.
When a Windows 2000 computer is booted, part of the startup process is to contact a DNS server to register its hostname and IP address. The TCP/IP properties can be configured to send the DNS server hostname and IP address registration data or, if the computer receives IP addressing information from a Windows 2000 DHCP server, the DHCP server can be configured to send the data to the DNS server.
Windows NT 4.0 Clients
Windows NT 4.0 (and previous versions of Windows NT) clients do not have the capability to send IP addressing information to a DNS server. There is some speculation that when Service Pack 7 for Windows NT 4.0 is released, it will provide the capability for a computer running Windows NT 4.0 to send dynamic update information to the DNS server.
Currently, for a Windows NT 4.0 client to be able to take advantage of the dynamic update capability of a DNS server, the client computer must be configured to receive IP addressing information from a Windows 2000 DHCP server. The DNS zone update process is performed by the DHCP server, as shown in Figure 3.9. This is true of any Windows client computer that cannot update DNS zone information.
Figure 3.9 DNS zone information can be updated by a Windows 2000 DHCP server on behalf of a Windows client computer that cannot update zone information.
Windows 9x Clients
Windows 9x clients cannot send the DNS server registration information. For a Windows 9x client to be able to take advantage of the dynamic update capabilities of the DNS server, the 9x client must be configured to receive IP addressing information from a Windows 2000 DHCP server. The DHCP server would then send the DNS the registration information on behalf of the DHCP client.
There is an Active Directory-aware client for computers running Windows 9x that gives the Windows 9x client the capability to function in a Windows 2000 Active Directory networking environment, but it does not provide the capability to send update information to the Windows 2000 DNS server.
NonActive Directory-aware clients do not have the capability to send dynamic update information to a Windows 2000 DNS server. For a computer that does not have the capability to send dynamic updates to a DNS server, the client must be a Windows 2000 DHCP server client, or resource records must be added to the DNS server manually.