If the target machine gains its Internet access using PPP rather than Ethernet, there will be some configuration necessary before access to the Internet can be established. The Debian Base System, comes with the PPP daemon installed, but not configured. Once configured, a PPP connection can be used to complete the installation, when necessary. Beginning with the 2.0 release, Debian has provided a PPP configuration utility, which will be offered at the first reboot after the installation of the base system. You should probably still read over the following information.
What will be described here is a simple connection to a service provider with no special authentication. This is the most common connection method and should work in most cases.