Network Topology is basically a description of how the physical connections of a network are set up. 对于一个网络，通常需要用网络拓扑来描述它的物理连接以及设置情况。
While it is not essential for an Intranet to have a physical connection into the Internet, the benefits can often outweigh the risks. 然而，内部网不必一定与互联网有物理连接，这样做常常是好处大于风险。
