Saturday, 10 November 2012

The TestKing network administrator needs to determine what LAN devices to install on the TestKing network. What are two advantages of using Layer 2 Ethernet switches over hubs? (Choose two)

A. Allowing simultaneous frame transmissions
B. Increasing the size of broadcast domains
C. Increasing the maximum length of UTP cabling between devices
D. Filtering frames based on MAC addresses
E. Decreasing the number of collision domains

Answer: A, D

Explanation:

A: A half duplex connection is where only one device can send or receive at a time. A full
duplex connection is where both devices can send and receive at the same time.
Thus, if you have a 100Mb half-duplex connection, only sending at 100Mb OR receiving
at 100Mb can happen at the same time. If you have a 100Mb full duplex connection, you
can effectively get 200Mb out of the link because you could be sending 100Mb and
receiving 100Mb at the same time.

D: Switches are capable of filtering frames based on any Layer 2 fields. For example, a
switch can be programmed to reject (not forward) all frames sourced from a particular
network. Because link layer information often includes a reference to an upper-layer
protocol, switches usually can filter on this parameter. Furthermore, filters can be helpful
in dealing with unnecessary broadcast and multicast packets.

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