NETGEAR SRX5308 Reference Manual page 43

If your network has a permanently assigned IP address, you can register a domain name and
have that name linked with your IP address by public Domain Name Servers (DNS).
However, if your Internet account uses a dynamically assigned IP address, you will not know
in advance what your IP address will be, and the address can change frequently—hence, the
need for a commercial DDNS service, which allows you to register an extension to its
domain, and restores DNS requests for the resulting FQDN to your frequently changing IP
address.
After you have configured your account information on the VPN firewall, when your
ISP-assigned IP address changes, your VPN firewall automatically contacts your DDNS
service provider, logs in to your account, and registers your new IP address. Consider the
following:
• For auto-rollover mode, you need a fully qualified domain name (FQDN) to implement
features such as exposed hosts and virtual private networks regardless of whether you
have a fixed or dynamic IP address.
• For load balancing mode, you might still need a fully qualified domain name (FQDN)
either for convenience or if you have a dynamic IP address.
Note: If your ISP assigns a private WAN IP address such as 192.168.x.x
or 10.x.x.x, the DDNS service does not work because private
addresses are not routed on the Internet.

To configure DDNS:
1. Select Network Configuration > Dynamic DNS. The Dynamic DNS screen displays
(see the following figure).
The WAN Mode section on the screen reports the currently configured WAN mode (for
example, Single Port WAN1, Load Balancing, or Auto Rollover). Only those options that
match the configured WAN mode are accessible on the screen.
2. Select the submenu tab for your DDNS service provider:
• Dynamic DNS (which is shown in the following figure) for DynDNS.org
• DNS TZO for TZO.com
• DNS Oray for Oray.net
• 3322 DDNS for 3322.org
ProSafe Gigabit Quad WAN SSL VPN Firewall SRX5308
Connecting the VPN Firewall to the Internet
43