ccna 640-802 s1-6~8/9@10/791

QUESTION NO: 6
Cisco is the leader in the router market space. What basic functions do their routers
perform in a network? (Choose two)
A. The microsegmentation of broadcast domains
B. Path selection
C. Packet switching
D. Bridging between LAN segments
E. Access layer security
F. VLAN membership assignment
G. Application optimization

Answer: B, C
Explanation:
The primary functions of a router are: Packet Switching and Path Selection. It is the
routers job to determine the best method for delivering the data, and switching that data
as quickly as possible.

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QUESTION NO: 7
Both bridges are switches are being used throughout the TestKing LAN. Which of
the following statements are true regarding bridges and switches in this network?
(Choose 3)
A. Switches are primarily software based while bridges are hardware based.
B. Switches usually have a higher number of ports than most bridges.
C. Bridges are frequently faster than switches.
D. Bridges define broadcast domains while switches define collision domains.
E. Both bridges and switches forward Layer 2 broadcasts.
F. Both bridges and switches make forwarding decisions based on Layer 2 addresses.

Answer: B, E, F

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QUESTION NO: 8
As a network administrator, you will need to decide on the appropriate network
devices to use. Which of the following correctly describes the roles of devices in a
WAN? (Choose three)
A. A CSU/DSU terminates a digital local loop.
B. A router is commonly considered a DCE device.
C. A modem terminates an analog local loop.
D. A router is commonly considered a DTE device.
E. A modem terminates a digital local loop.
F. A CSU/DSU terminates an analog local loop.
G. A modem is used to terminate a T1

Answer: A, C, D
Explanation:
Layer 2 switching is considered hardware-based bridging because it uses specialized
hardware called an application-specific integrated circuit (ASIC). ASICs can run up to
gigabit speeds with very low latency rates.
Switches usually have higher port number then bridge. Generally bridges have two ports.
Both operates on Data link layer.

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DSU/CSU　Channel Service Unit/Data Service Unit。資料服務通道/通道服務單位。
是用戶端（User End）與電信局局端（Central Office）間E1/T1線路傳輸的數位式數據機，也是WAN與LAN間的基礎介質，具有傳輸語音、數據和影像的功能，CSU/DSU通常合併放在一個硬體中連結在一起使用。CSU負責傳送與接收往返WAN的訊號、測試迴路是否已中斷連線，並可檢測另一端的DSU/CSU是否正常運作；DSU則負責管理與轉換在RS-232C、RS-449或V.xx架構間的輸出輸入訊號，可檢測時間錯誤與恢復信號。

Ref>
http://en.wikipedia.org/wiki/CSU/DSU