In our laptop, we can have up to two physical ethernet interfaces attached at any time. The machine can be connected to its ethernet-enabled docking station, it can have a PCMCIA ethernet card installed, or it can have both or neither of those.
The docking station interface is connected to a LAN where it is necessary to give the laptop a static IP address. The PCMCIA card, however, is more typically used in the field and is likely to have access to DHCP services when used. In no case is the PCMCIA card used, whether it is physically inserted or not, when the laptop is in its docking station.
Linux names its ethernet interfaces ethn where n is sequentially assigned in the order interfaces are discovered or their modules loaded. This means we cannot count on any particular name assignment for our interfaces.Next: How Debian Configures Interfaces 11/16/2001 Greg Wiley