Default Gateway

The Internet and even the Missouri State University campus network is so large that a single network cannot handle all of the traffic and still deliver a reasonable level of service.  To overcome this limitation, the network is broken down into smaller segments or subnets that can deliver good performance for the stations attached to that segment.  This segmentation solves the problem of supporting a large number of stations, but introduces the problem of getting traffic from one subnet to another.

To accomplish this, devices called routers or gateways are placed between segments.  If a machine wishes to contact another device on the same segment, it transmits to that station directly using a simple discovery technique.  If the target station does not exist on the same segment as the source station, then the source actually has no idea how to get to the target.

One of the configuration parameters transmitted to each network device is it's default gateway.  This address is configured by the network administrators and it informs each personal computer or other network device where to send data if the target station does not reside on the same subnet as the source.  If your machine can reach all stations on the same subnet (usually a building or a sector within a building), but cannot communicate outside of this area, it is usually because of an incorrectly configured default gateway.