● Routing protocols use different techniques for assigning__(71)__to individual networks．Further，  each routing protocol forms a metric aggregation in a different way. Most routing protocols can use multiple paths if the paths have an equal__(72)__.Some routing protocols can even use multiple paths when paths have an unequal cost.In either case，load__(73)__can improve overall allocation of network bandwidth．When multiple paths are used，there are several ways to distribute the packets. The two most common mechanisms are per-packet load balancing and per-destination load balancing.Per-packet load balancing distributes the__(74)__across the possible routes in a manner proportional to the route metrics，Per-destination load balancing distributes packets across the possible routes based on__(75)__.

（71）A．calls　

B．metrics

C．links  　

D．destinations

（72）A．user  

B．distance　

C．entity

D．cost

（73）A．bracketing　

B．balancing　

C．downloading　

D．transmitting

（74）A．destinations　

B．Resources 

C．packets

D．sources

（75）A．destinations

B．resources　

C．packets

D．sources