Cisco Systems 2 manual 141

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Incorrect Answers:

A is incorrect; is this series of commands the network 10.1.0.1 is not a valid command.

C is incorrect; if 4 networks are directly connected they must have their own network command. D is incorrect; there is no need to include a subnet mask with a network command.

Steve McQuerry. Interconnecting Cisco Network Devices. (Cisco Press: 2000) pages 278-9.

Q. 228

Which one method for transporting frames through a switch which checks the destination address in the frame header immediately begins forwarding the frame. What is this frame transmission method called?

A.CSMA/CD

B.FULL DUPLEX

C.CUT THROUGH

D.HALF DUPLEX

E.FRAGMENTATION

F.STORE AND FORWARD

Answer: C.

Explanation:

In cut-through mode, the switch checks the destination address (DA) as soon as the header is received and immediately begins forwarding the frame. Depending on the network transport protocol being used (connection or connectionless orientate), there is a significant decrease in latency from input port to output port. The delay in cut-through switching remains constant regardless of the size of the frame , because this switching mode starts to forward the frame as soon as the switch reads the DA.

Incorrect Answers:

A is incorrect; CSMA/CD is not a method of transporting frames. Rather it is a set of rules that are used to determine how network devices will respond to two different devices attempting to communicate on a data channel at the same time.

B is incorrect; Full duplex refers to how two switches communicate with each other. In this case, there is a transmission of data in two directions at the same time.

D is incorrect; half duplex refers to how two switches communicate with each other. With half duplex the communication can only be in one direction and if not a collision will occur.

E is incorrect; this is not a method of frame communication.

F is incorrect; in store and forward the entire frame must first be received before it can be forwarded on.

Steve McQuerry. Interconnecting Cisco Network Devices. (Cisco Press: 2000) pages 162-5.

Q. 229

Which two statements about the Frame Tagging are true? (Choose two)

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