Configuring DHCP to send dynamic updates to DNS

 

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 i5/OS^®) 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:

1. Expand Network > Servers > TCP/IP.

2. In the right pane, right-click DHCP and select Configuration.

3. In the left panel of the DHCP Server Configuration window, right-click Global and select Properties.

4. Select the Options tab.

5. 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.

6. In the Domain Name field, specify the domain name the client uses when resolving host names using DNS.

7. Select the Dynamic DNS tab.

8. Select DHCP server updates both A records and PTR records or DHCP server updates PTR records only.

9. Set Append domain name to host name to Yes.

10. 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