When an IPv4 DHCP client sends DHCP DISCOVER and DHCP REQUEST messages, it can include option 81, the Client FQDN option. The Client FQDN option contains the FQDN (fully qualified domain name) of the client and instructions on whether the client or the server performs DDNS updates. You can configure the application to replace the FQDN in the option by defining a hostname NIOS-X Server name rewrite policy. For information about adding and enabling a hostname NIOS-X Server name rewrite policy, see Replacing Host NIOS-X Server Names for DDNS Updates.
The DHCP server can support option 81 for IPv4 clients, and use the FQDN that the client provides for the update. It can also allow or deny the client’s request to update DNS, according to the administrative policies of your organization. The DHCP server indicates its response in the DHCP OFFER message it sends back to an IPv4 client.