固定成本的特点有（ ）

A．成本总额随业务量的增减变动成正比例变动

B．单位业务量的固定成本不受业务量增减变动的影响

C．成本总额不随业务量的增减变动而变动

D．单位业务量的固定成本随业务量增减变动成正比例变动

E．单位业务量的固定成本随业务量增减变动成反比例变动

Border Gateway Protocol(BGP) is inter-autonomous system ______ protocol. BGP is based ona routing method called path vector routing. Distance vector routing is not a good candidate for inter-autonomoussystem routing because there are occasions on which the route with the smallest ______ count is not thepreferred route. For example, we may not want a packet through an autonomous system that is not secure eventhough it is shortest route. Also, distance vector routing is unstable due to the fact that the routers announce onlythe number of hop counts to the destination without defining the path that leads to that ______. A router thatreceives a distance vector advertisement packet may be fooled if the shortest path is actually calculated throughthe receiving router itself. Link ______ routing is also not a good candidate for inner-autonomous system routingbecause an internet is usually too big for this routing method. To use link state routing for the whole internetwould require each router to have a huge link state database. It would also take a long time for each router tocalculate its routing ______ using the Dijkstra algorism.

A．routing

B．switching

C．transmitting

D．receiving