The metric assigned to each network depends on the type of protocol. Some simple protocol, like RIP, treats each network as equals. The ___44___ of passing through each network is the same; it is one ___45___ count. So if a packet passes through 10 network to reach the destination, the total cost is 10 hop counts. Other protocols, such as OSPF, allow the administrator to assign a cost for passing through a network based on the type of service required.A ___46___ through a network can have different costs (metrics). For example, if maximum ___47___ is the desired type of service, a satellite link has a lower metric than a fiber-optic line. On the other hand, if minimum ___48___ is the desired type of service, a fiber-optic line has a lower metric than a satellite line. OSPF allow each router to have several routing table based on the required type of service.

44（）

A. cost

B. link-state

C. connection

D. diagram

共用天线电视系统，前端信号的来源有( )。

A．无线电视台信号

B．卫星地面接收信号

C．有线电视台传输信号

D．各种自办节目信号

E．广播信号