An internet is a combination of networks connected by （） . When a datagram goes from a source to a （） , it will probably pass many （） until it reaches the router attached to the destination network. A router receives a （） from a network and passes it to another network. A router is usually attached to several networks. When it receives a packet, to which network should it pass the packet The decision is based on optimization: Which of the available （） is the optimum pathway
An internet is a combination of networks connected by （）.
A．modems
B．routers
C．switches
D．computers