A.aggregation congestion occurring at the core layer where the different distribution layer devices feed traffic to the core-layer switches
B.speed mismatches when moving from a low-speed LAN environment to a higher speed WAN environment
C.flapping Ethernet interfaces caused by misconfigured LAN interfaces
D.flapping serial interfaces caused by misconfigured WAN interfaces
E.speed mismatches when moving from a high-speed LAN environment to a lower speed WAN environment

A.over leased lines， use the multilink ppp command to reduce latency and jitter， and to create Distributed Link Fragmentation and interleaving
B.use the service-policy command to attach a traffic flow to an interface on the router
C.use the ip rsvp bandwidth command to set a strict upper limit on the bandwidth NBAR uses， and to guarantee admission of any flows
D.use the policy-map command to define one or more QoS policies （such as shaping， policing， and so on） to apply to traffic defined by a class map
E.use the random-detect dscp command to modify the default minimum and maximum thresholds for the DSCP value
F.use the class-map command to define one or more traffic classes by specifying the criteria by which traffic is classified

A.apply the clock rate 64000 command on both serial interfaces connected to the WAN link
B.apply the bandwidth 64 command on both serial interfaces connected to the WAN link
C.apply the frame-relay voice-bandwidth 64000 command to enable the QoS Call Admission Control feature on the serial link
D.apply the max-conn 64 command on a perial peer basis on both sides of the serial link
E.apply the ip bandwidth-percent eigrp 1 64 command on both sides of the serial link
F.apply the auto-cost reference-bandwidth 64 command on both sides of the serial link

A.the DiffServ model requires applications to signal the network with QoS requirements
B.the DiffServ model can be used to deliver QoS based upon IP precedence， or source and destination addresses
C.the DiffServ model requires RSVP
D.the best effort model is suitable for applications such as file transfer and e-mail
E.the IntServ model requires applications to signal the network with QoS requirements
F.the IntServ model model attempts to deliver a level of service based on the QoS specified by each packet

A.centralized management for autonomous access points 
B.centralized management for lightweight access points
C.centralized management that requires an external AAA server 
D.centralized management with integrated AAA server
E.integration with the Location Appliance to expand real time tracking to 1500 devices for 30 days 
F.integration with the Location Appliance to expand real time tracking to 2500 devices for 30 days