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Wednesday, October 16, 2013

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CCNA Discovery: Introducing Routing and Switching in the Enterprise (Version 4.0) –Chapter 7 Answers – 2013 – 2014

1. Why are Network Control Protocols used in PPP? 
• to establish and terminate data links 
• to provide authentication capabilities to PPP 
• to manage network congestion and to allow quality testing of the link 
• to allow multiple Layer 3 protocols to operate over the same physical link 

2. What is the data transmission rate for the DS0 standard? 
• 44 kb/s 
• 64 kb/s 
• 1.544 Mb/s 
• 44.736 Mb/s 

3. In which two layers of the OSI model are key differences found between a LAN and a WAN. (Choose two.) 
• Layer 1
• Layer 2
 
• Layer 3 
• Layer 4 
• Layer 6 
• Layer 7 

4. Which statement is true about the Cisco implementation of the HDLC protocol? 
• It supports authentication. 
• It has a universally compatible frame format. 
• It is the default encapsulation for serial interfaces on Cisco routers. 
• It does not support multiple protocols across a single link. 

5. 
image 
Refer to the exhibit. A network administrator has a connectivity problem between the serial interfaces of Merida and Vargas. What is the cause of the problem? 
• Authentication is required on the serial link. 
• The encapsulation is misconfigured. 
• The IP addresses are on different subnets. 
• The serial interface on Vargas is shutdown. 
• The loopback interfaces on both routers are not configured. 

6. 
image 
Refer to the exhibit. What statement is true about the exhibited output? 
• LCP is in the process of negotiating a link. 
• LCP and NCP are waiting for CHAP authentication to complete. 
• LCP negotiation has completed successfully, but NCP negotiation is in progress. 
• LCP and NCP negotiation is complete, and the data link service is available to carry packets. 

7. Which three statements are true regarding LCP? (Choose three.) 
• It is responsible for negotiating link establishment. 
• It negotiates options for Layer 3 protocols running over PPP. 
• It uses MD5 encryption while negotiating link-establishment parameters. 
• It terminates the link upon user request or the expiration of an inactivity timer.
• It can test the link to determine if link quality is sufficient to bring up the link.
 
• It monitors the link for congestion and dynamically adjusts the acceptable window size. 

8. Why are Frame Relay paths referred to as virtual? 
• Frame Relay PVCs are created and discarded on demand. 
• The connections between PVC endpoints act like dialup circuits. 
• There are no dedicated circuits to and from the Frame Relay carrier. 
• The physical circuits inside the Frame Relay cloud do not contain exclusive links for a specific Frame Relay connection. 

9. What best describes the use of a data-link connection identifier (DLCI)? 
• an address identifying a virtual circuit 
• a logical address identifying the DCE device 
• an address identifying a Layer 3 service across a Frame Relay network 
• a logical address identifying the physical interface between a router and a Frame Relay switch 

10. What two services allow the router to dynamically map data link layer addresses to network layer addresses Frame Relay network? (Choose two.) 
• ARP 
• ICMP 
• Proxy ARP 
• Inverse ARP
• LMI status messages
 

11. Which three statements describe functions of the Point-to-Point Protocol with regards to the OSI model?(Choose three.) 
• operates at all layers of the OSI model 
• provides a mechanism to multiplex several network layer protocols
• can be configured on both synchronous and asynchronous serial interfaces
 
• uses Layer 3 of the OSI model to establish and maintain a session between devices 
• uses the data link layer to configure such options as error detection and compression 
• uses network control protocols to test and maintain connectivity between devices 

12. At what physical location does the responsibility for a WAN connection change from the user to the service provider? 
• demilitarized zone (DMZ) 
• demarcation point 
• local loop 
• cloud 

13. What does a Frame Relay switch use to inform the sender that there is congestion? 
• FECN 
• BECN 
• DE 
• FCS 

14. 
image 
Refer to the exhibit. What statement is true about the debug output? 
• R2 is using PAP instead of CHAP. 
• The routers have different CHAP passwords configured. 
• The administrator performed a shutdown on the R2 PPP interface during negotiation. 
• The Layer 3 protocol negotiation caused the connection failure. 

15. Which two statements describe the function of time-division multiplexing? (Choose two.) 
• Multiple data streams share one common channel. 
• Conversations that require extra bandwidth receive any unused time slices. 
• Time slots are utilized on a first-come, first-served basis. 
• Time slots go unused if a sender has nothing to transmit. 
• Priority can be dedicated to one data source. 

16. When customers use credit cards to make purchases at a small business, a modem is heard dialing a telephone number to transfer the transaction data to the central office. What type of WAN serial connection is in use? 
• leased line 
• point-to-point 
• circuit switched 
• packet switched 

17. Which best describes data communications equipment (DCE)? 
• serves as data source and/or destination 
• responsible for negotiating windowing and acknowledgements 
• physical devices such as protocol translators and multiplexers 
• equipment that forwards data and is responsible for the clocking signal 

18. Permanent virtual circuits and switched virtual circuits are both part of which option for WAN connectivity? 
• leased line 
• cell switching 
• packet switching 
• circuit switching 

19. Which field of a frame uses error detection mechanisms to verify that the frame is not damaged intransit? 
• FCS 
• MTU 
• flag 
• control 
• protocol 

20. What occurs in the encapsulation process as a data packet moves from a LAN across a WAN? 
• The Layer 2 encapsulation changes to a format that is appropriate for the WAN technology. 
• The Layer 3 encapsulation changes to a format that is appropriate for the WAN technology. 
• Both Layer 2 and Layer 3 encapsulation change to a technology that is appropriate for the WAN.
• Both Layer 2 and Layer 3 encapsulation remain constant as the data packet travels throughout the network. 

21. 
image 
Refer to the exhibit. The network administrator is configuring R1 to connect to R2, which is a non-Cisco router. Which encapsulation method will need to be configured for communication to occur?
• HDLC 
• HSSI 
• ISDN 
• IPCP 
• PPP 

22. A company is implementing dialup services for remote workers to connect to the local network. The company uses multiple Layer 3 protocols and requires authentication for security. Which protocol should be used for this remote access? 
• LMI 
• PPP 
• HDLC 
• Frame Relay 

23. Which two options can LCP negotiate? (Choose two.) 
• compression
• authentication 
• dynamic flow control 
• network layer address for IP 
• connection-oriented or connectionless communication methods 

24. What statement best describes cell switching? 
• It uses a dedicated path between endpoints. 
• It creates a permanent physical link between two points. 
• It uses DLCIs to identify virtual circuits. 
• It creates fixed-length packets that traverse virtual circuits.

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