- What is NAT? Is this something that I want?
Generally, yes. NAT allows you to use "fake" IP addresses for your internal network (LAN). It's good because it provides an inexpensive firewall since no one can get to these fake IPs. It also gives you as many IP addresses for your LAN as you want; you don't have to ask us for more.
When wouldn't you want to use NAT? When you have more than one of the same internet service running, like several mail servers or several web servers. Most offices don't have the need for this. We recommend NAT whenever possible.