Netopia R2121 User Reference Manual page 111

Follow these steps to configure IP Setup for your Netopia R2121:
Select Ethernet IP Address and enter the IP address for the Netopia R2121's Ethernet port.
Select Ethernet Subnet Mask and enter the subnet mask for the Ethernet IP Address that you entered in
the last step.
Select Default IP Gateway and enter the IP address for a default gateway. This can be the address of any
major router accessible to the Netopia R2121.
A default gateway should be able to successfully route packets when the Netopia R2121 cannot recognize
the intended recipient's IP address. A typical example of a default gateway is the ISP's router.
Select DNS Server and enter the IP address for a domain name server. The domain name server matches
the alphabetic addresses favored by people (for example, robin.hood.com) to the IP addresses actually
used by IP routers (for example, 163.7.8.202).
If a secondary DNS server is available, select Secondary DNS Server and enter its IP address. The
secondary DNS server is used by the Netopia R2121 when the primary DNS server is inaccessible.
Entering a secondary DNS is useful but it is not necessary.
Select Domain Name and enter your network's domain name (for example, netopia.com). Entering a
Domain Name is strongly recommended.
Select Exported Services. The Exported Services screen appears with three options, Show/Change
Exports, Add Export, and Delete Export.
IP Setup, SmartIP and Network Address Translation 10-7
Exported Services
(Local Port to IP Address Remapping)
Show/Change Exports...
Add Export...
Delete Export...