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CCNA 4 Module 1 V4.0

| Monday, April 27, 2009
1. At which two layers of the OSI model does a WAN operate? (Choose two.)
**Physical Layer
**Data Link Layer
Network Layer
Transport Layer
Presentation Layer
Application Layer

2. Which three WAN devices can be found in the cloud? (Choose three.)
** ATM switches
**core routers
Ethernet switches
**Frame Relay switches

3. Which networking device is typically used to concentrate the dialin and dialout traffic of multiple users to and from a network?
core router
** access server
Frame Relay switch
ATM switch

4. Which packetswitched WAN technology offers highbandwidth connectivity capable of managing data, voice, and video all on the same infrastructure?
Time Division Multiplexing (TDM)
**metro Ethernet
Integrated Services Digital Network (ISDN)
Public Switched Telephone Network (PSTN)

5. Which three features are identified with Frame Relay connections? (Choose three.)
** CIR
** PVC
53byte cells

6. Which WAN technology uses a fixed payload of 48 bytes and is transported across both switched and permanent virtual circuits?
Frame Relay
metro Ethernet

7. What are two advantages of an analog PSTN WAN connection? (Choose two.)
** low cost
** availability
traffic encryption
available bandwidth
support for voice and video

8. What three terms are associated with ISDN PRI? (Choose three.)
** circuit switching
packet switching
** data bearer channels
switched virtual circuits
** time-division multiplexing

9. What can cause a reduction in available bandwidth on a cable broadband connection?
smaller cells
** number of subscribers
committed information rate
distance from the central office of the provider

10. What type of connectivity is established when VPNs are used from the remote site to the private network?
virtual circuits
dedicated Layer 2 links

11. A U.S. company requires a WAN connection used only to transfer sales data from individual stores to the home office. All transfers will occur after business hours. The required bandwidth for this connection is estimated to be less than 38 kbps. Which type of connection requires the least investment for this company?
** analog dialup
T1 Leased Line

12. For digital lines, which device is used to establish the communications link between the customer equipment and the local loop?
Frame Relay switch
ISDN switch
PBX switch

13. Which term describes a device that will put data on the local loop?
** DCE

14. Which switching type will allow the communication devices in the provider network to be shared and only allocated to an individual subscriber during data transfer?
dedicated switched lines

15. A company needs a WAN connection that is capable of transferring voice, video, and data at a minimum data rate of 155 Mbps. Which WAN connection is the best choice?
** ATM

16. Which two devices are commonly used as data communications equipment? (Choose two.)
** modem
ISDN switch
Ethernet switch

17. Which statement is true of the functionality of the layers in the hierarchical network model?
The purpose of the access layer is to provide very high bandwidth communications between network devices.
Most security screening to prevent unauthorized entry to the network happens at the core layer.
Untrusted external connections are segmented from the rest of the network at all three levels.
The core layer uses high speed equipment to provide policybased connectivity.
** The distribution layer aggregates WAN connections at the edge of the campus.

18. Which statement is true about data connectivity between a customer and a service provider?
Normally the CSU/DSU is the designated demarcation point for the service provider but not the customer.
** The segment between the demarcation point and the central office is known as the "last mile."
The local loop is the segment between the CSU/DSU and the serial port on a router.
Putting data on the local loop is the responsibility of the DTE.

19. Which statement is true about the differences between a WAN and a LAN?
WANs generally support higher bandwidth than LANs support.
A WAN link typically traverses shorter geographic distances than a LAN link traverses.
** A WAN often relies on the services of carriers, such as telephone or cable companies, but a LAN does not.
All WAN implementations generally use the same Layer 2 protocol but there are many accepted LAN Layer 2 protocols in use.

20. Why is the call setup time of a circuitswitched WAN implementation considered a drawback?
Routing protocols are incompatible with this function.
It restricts the communication sent to voice traffic only.
A telephone must be used to initially start transferring data.
**Data cannot be transferred until a circuit has been established.

21. Which statement about WAN protocols is correct?
ATM differs from other WAN protocols in that it uses variably sized packets.
** Most WAN protocols use HDLC or a variant of HDLC as a framing mechanism.
The frame header consists of the frame check sequence and cyclic redundancy check.
ISDN differs from Frame Relay, HDLC, and ATM in that it is packetswitched rather than circuitswitched technology.

22. What is an advantage of packetswitched technology over circuitswitched technology?
Packetswitched networks are less susceptible to jitter than circuitswitched networks are.
** Packetswitched networks can efficiently use multiple routes inside a service provider network.
Packetswitched networks do not require an expensive permanent connection to each endpoint.
Packetswitched networks usually experience lower latency than circuitswitched networks experience.


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