An internet is a combination of networks connected by (71) .When a datagram goes from a source to a (72) ，it will probably pass many (73) until it reaches the router attached to the destination network．A router receives a (74) 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 (75) is the optimum pathway?

A network administrator wants to control which user hosts can access the network based on their MAC address. What will prevent workstations with unauthorized MAC addresses from connecting to the network through a switch?（）

A network administrator wants to control which user hosts can access the network based on their MAC address. What will prevent workstations with unauthorized MAC addresses from connecting to the network through a switch?

Given the network diagram, which routers currently make up the IS - IS  backbone?（）

Which OSPF router will advertise a Type 2 network LSA for a broadcast network segment?（）

A common technique used to prevent the unauthorized network devices from sending trafficacross a network is port（）

Given the network diagram, which address would successfully summarize only the networks seen? （）

A( ) is a computer commtuucation network in a local area, which connects various computers.

A time diagram is a diagram of the celestial sphere as observed from above the（）.

A．活动图(activity diagram)

In project network diagram，the number of critical path is（）.

UML通过图形化的表示机制从多个侧面对系统的分析和设计模型进行刻画。其中（）包括交互图（interactive diagram）、状态图（statechart diagram）与活动图（activity diagram），它们从不同的侧面刻画系统的动态行为。