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.

48（）

A．bandwidth

B．efficiency

C．availability

D．delay

下列有关电子地图功能的叙述,不正确的是

A．电子地图能储存有关道路的基本信息,方便人们选择最佳路径

B．利用电子地图可动态监控工矿企业的排污状况

C．装有语音识别系统的电子地图可为盲人引路

D．电子地图不能附加多种智能化服务功能