Configuring Dynamic Updates with DHCP

By default, post-Windows 2000 DHCP clients attempt to perform dynamic updates of their host (A) resource records in DNS whenever an address event (such as an address renewal) occurs. However, these same clients do not attempt to perform dynamic updates of their PTR resource records; instead, post-Windows 2000 DHCP clients request that the DHCP server attempt to update their PTR resource records in DNS on behalf of the client.
Default DNS Update Settings for DHCP Servers

By default, a DHCP server registers records on behalf of a DHCP client only according to client request. That is, because the DHCP client by default requests that the server update only the client's PTR resource records, the DHCP server attempts only this type of update. However, a server can also be configured to attempt an update of both A and PTR resource records, regardless of the client request.

source by NetworkingForBeginners

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