思科认证

思科认证:CCNA认证模拟试题练习及答案82

时间: 2013-10-10

71. which layer is responsible for providing mechanisms for multiplexing upper-layer application, session establishment, and tear-down of virtual circuits?  
a. application  
b. presentation  
c. session  
d. transport  
answer d.  
72. which layer is responsible for coordinating communication between systems?  
a. application  
b. presentation  
c. session  
d. physical  
answer c.  
73. which layer is responsible for negotiating data transfer syntax?  
a. application  
b. presentation  
c. session  
d. transport  
answer b.  
74. which of the following is a characteristic of a switch, but not of a repeater?  
a. switches forward packets based on the ipx or ip address in the frame.  
b. switches forward packets based only on the ip address in the packet.   
c. switches forward packets based on the ip address in the frame   
d. switches forward packets based on the mac address in the frame  
answer d. switches are network device that filters, forwards, and floods frames based on the destination address of each frame. the switch operates at the data link layer of the osi model. switches use layer 2 addresses to filter the network  vK)R 
75. how does the cut-through switching technique work?   
a. the lan switch copies the entire frame into its buffers and then looks up the destination address in its forwarding, table and determines the outgoing interface   
b. the switch waits only for the header to be received before it checks the destination address and starts forwarding the packets   
c. by using broadcast addresses as source addresses   
d. by using a class ii repeater in a collision domain   
answer b. packet switching approach that streams data through a switch so that the leading edge of a packet exits the switch at the output port before the packet finishes entering the input port. a device using cut-through packet switching reads, processes, and forwards packets as soon as the destination address is looked up, and the outgoing port determined. also known as on-the-fly packet switching.  


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