This article explains how to configure Dynamic DNS on SRX devices so that the servers protected by the device remain accessible despite dynamic IP address changes.

How does a user configure Dynamic DNS (DDNS) so that the servers protected by the device remain accessible despite dynamic IP address changes?

SRX maintains the list of changed addresses and their associated domain names. The device updates the DDNS servers with this information periodically, or whenever there is a change in IP addresses.

For example, a protected Web server continues to be accessible with the same hostname, even after the dynamic IP address is changed, because of address reassignment by the Dynamic Host Configuration Protocol (DHCP) or Point-to-Point Protocol (PPP) by the Internet service provider (ISP).

To configure DDNS on SRX, the following parameters must be configured under system services:

• Hostname: Internal DNS Hostname of the registered client
• Server: DDNS server name ( members.ddnsserver.org or ddnsserver.jp ) that allows dynamic DNS clients to update the IP address changes associated with the registered hostname.
• Agent: Name of the DDNS agent
• Interface: Interface whose IP address is mapped to the registered domain name.
• username: Specifies the dynamic DNS server username
• password: Specifies the password

Here is a sample syntax file to configure DDNS via the command line interface:

Please note that this feature is introduced in Junos OS Release 12.1X44-D10 and hence D-DNS cannot be configured on earlier releases .

Verification:

To verify if the configuration is working properly:

• show system services dynamic-dns