ccna 640-802 s1-4~5@9/791

QUESTION NO: 4

Which of the following correctly describe the various functions and virtues of a
router? (Select all valid answer choices)
A. Packet switching
B. Collision prevention on a LAN segment.
C. Packet filtering
D. Broadcast domain enlargement
E. Broadcast forwarding
F. Internetwork communication
G. None of the above

Answer: A, C, F
Explanation:
The main function of a router is to connect different, separated networks together. In
doing so, switching packets from one network to another is a primary function, along
with providing for communication between networks. As an additional feature, routers
are capable of providing filtering on a network address and application port level, so
choice C is also correct.
Incorrect Answers:
B. Routers can indeed be used to segment a network separate a collision domain, since
routers do not forward LAN broadcasts and multicasts to other interfaces. However,
routers alone can not prevent all collisions from occurring on any given LAN segment.
D. Routers actually segment LANs into smaller broadcast domains.
E. Routers do not forward broadcast and multicast traffic out the additional interfaces by
default. Unless bridging or IP helpers are configured on the router, LAN broadcasts are
blocked at the router level.

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QUESTION NO: 5

The LAN needs are expanding at the Testking corporate office, which is quickly
growing. You are instructed to enlarge the area covered by a single LAN segment on
the TestKing network.
Which of the following are layer 1 devices that you can use? (Choose all that apply.)
A. A switch
B. A router
C. A network adapter card
D. A hub
E. A repeater

Answer: D, E
Explanation:
A hub simply repeats the electrical signal and makes no attempt to interpret the electrical
signal (layer 1) as a LAN frame (Layer 2). So, a hub actually performs OSI layer 1
functions, repeating an electrical signal, whereas a switch performs OSI layer 2 functions,
actually interpreting Ethernet header information, particularly addresses, to make
forwarding decisions. Hubs can be used to increase the number of stations that can be
supported on a LAN.
Because the repeater does not interpret what the bits mean, but does examine and
generate electrical signals, a repeater is considered to operate at Layer 1. Repeaters can be
used to physically extend the LAN to greater distances.