Configuring DHCP to send dynamic updates to DNS

Last Updated: 2021-08-31

The Dynamic Host Configuration Protocol (DHCP) server can be configured to
send update requests to the DNS server each time it assigns a new address to
a host. This automated process reduces DNS server administration in rapidly
growing or changing TCP/IP networks, and in networks where hosts change
locations frequently.

When a client using DHCP receives an IP address, that data is immediately
sent to the DNS server. Using this method, DNS can continue to successfully
resolve queries for hosts, even when their IP addresses change.

For record updates to occur, Domain Name System (Option 31 of IBM® i) must
be installed on this server. The DHCP server uses programming interfaces
provided by Option 31 to perform dynamic updates. The DNS server can be
running on a separate System i® model that is capable of performing dynamic
updates. For information about verifying that Option 31 is installed, refer
to DNS system requirements.

To configure DHCP properties to allow the DHCP server to perform dynamic DNS
updates, follow these steps:

 Expand Network > Servers > TCP/IP.
 In the right pane, right-click DHCP and select Configuration.
 In the left panel of the DHCP Server Configuration window, right-click
Global and select Properties.
 Select the Options tab.
 Select option 15: Domain name from the Selected options list. If option 15
does not appear in the Selected options list, select 15: Domain name from
the Available options list and click Add.
 In the Domain Name field, specify the domain name the client uses when
resolving host names using DNS.
 Select the Dynamic DNS tab.
 Select DHCP server updates both A records and PTR records or DHCP server
updates PTR records only.
 Set Append domain name to host name to Yes.
 Click OK to close the Global Properties page.




Disabling DNS dynamic updates
By disabling the Domain Name System (DNS) dynamic updates function, the
responsibility of managing the DNS server is returned to the administrator.
Disabling DNS dynamic updates might be suitable for networks where hosts
rarely change locations, where growth and change are infrequent, and when
stricter DNS server administration is required.

Parent topic:
Configuring DHCP
Related concepts:
Dynamic updates