As long as we're setting up network services, we may as well go all the way and set up a router to act as a gateway for our network. In most commercial routers, we'll have DNS and DHCP built-in, as well as routing. Quite often, these services will all run on the same box. Depending on how you set up your DNS and DHCP servers in the previous sections, you may have even set up your primary DNS and DHCP servers on the same machine, which is quite common. However, your Internet connection will likely be terminated on a separate box, possibly a commercial routing device or Internet gateway from your Internet service provider.
Depending on what kind of Internet connection you have, Linux itself can likely replace whatever device that your Internet modem connects to. A good example of this is a cable modem that your office or home router may utilize. In this case, the modem provides your Internet connection, and then your router allows other devices on your network...