36.1.3 Dynamic DNS linkage

The DHCP server of the Switch distributes IP addresses and adds entry records to a dynamic DNS server (DNS updates). For DNS updates to take place, you need to specify the target zone and the target DNS server on the DHCP server, and configure the DNS server to receive record updates from the Switch.

Record updates are permitted either based on IP address or by using an HMAC-MD5 authentication key. For permission based on IP address, the DNS server simply permits access from the IP addresses of the clients or networks connected to the DNS server. For permission using an authentication key, you need to set the key specified for the DNS server in the DNS authentication key information on the DHCP server.

Notes on linking dynamic DNS

• The DHCP server of the Switch only performs DNS updating for the IP addresses that are dynamically assigned. If the DHCP server distributes static addresses, you need to add the corresponding records to the DNS server beforehand.

• To enable DNS updates, a DHCP client must return its FQDN to the DHCP server when it receives a distributed IP address. If the required information does not exist, the DHCP server does not perform DNS updating for the leased IP addresses. For details about the settings, see the configuration of the devices used as clients.

• When you use an authentication key for DNS updates, the DNS server and the Switch must have the same time information. In many cases, the time difference must be no more than five minutes in UTC. Use NTP to synchronize the time information.