642-437 by Cisco Valid Free Exam Practice Test

Question 1

When marking traffic for Expedited Forwarding, how does a device that is not capable of recognizing DSCP interpret the EF binary string 101110?

A. The device that does not recognize DSCP will use 110 as the CoS value and forward the packet with a CoS of 6. B. The first device in the network that does not recognize DSCP will use 110 as the CoS value and will replace the DSCP value with a CoS of 6 and forward the packet. C. The device that cannot recognize DSCP will use best effort to forward the packet. D. The devices in the network that do not recognize DSCP will use the three high-order DSCP bits as the CoS setting, resulting in a CoS value of 5.

Correct Answer: D

Question 2

When you implement the tail-end hop-off path-selection strategy, which task should you complete first?

A. Define the VoIP outbound digit manipulation. B. Define the outbound VoIP dial peer. C. Define the VoIP inbound digit manipulation. D. Define the inbound VoIP dial peer.

Correct Answer: A

Question 3

If a packet is marked with an IP precedence value of 011, what is the corresponding binary DSCP class-selector value?

A. 011000 B. 011010 C. 000011 D. 011110 E. 011100

Correct Answer: A

Question 4

At what point in a VoIP network are the existing class of service or differentiated services code point values considered valid and are used throughout the rest of the network?

A. distribution layer B. trust boundary C. marking boundary D. access layer

Correct Answer: B

Question 5

Which type of analog voice port would be used on a telephony device to connect to a telephone or fax machine?

A. Foreign Exchange Office B. ear and mouth C. Foreign Exchange Station D. T1

Correct Answer: C

Question 6

If a centralized solution has to be implemented on multiple-equipment vendors devices, which signaling protocol should be used?

A. Skinny Client Control Protocol B. Session Initiation Protocol C. Media Gateway Control Protocol D. H.323 protocol

Correct Answer: C

Question 7

You are configuring a network to support voice to the PSTN. One important aspect to the configuration is to be able to determine the individual slot, subunit, and port number from the gateway endpoint identifier. Which signaling protocol is appropriate for this situation?

A. SIP B. H.323 C. SCCP D. MGCP

Correct Answer: D

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Question 8

What is the command sequence to configure an FXS port as a signal loop-start?

A. router(config)# voice-port slot/port router(config-voiceport)# signal loopstart B. router(config)# voice-port slot/port router(config-voiceport)# signal groundstart C. router(config)# voice-port slot/port router(config-voiceport)# signal loopstart router(config-voiceport)# shutdown router(config-voiceport)# no shutdown D. router(config)# voice-port slot/port router(config-voiceport)# signal groundstart router(config-voiceport)# shutdown router(config-voiceport)# no shutdown

Correct Answer: C

Question 9

Which codec complexity type will offer the greatest number of voice channels, provided that the complexity type is compatible with the particular codecs that are in use?

A. medium complexity B. low complexity C. high complexity D. flex complexity

Correct Answer: B

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Question 10

DRAG DROP
Drag the statement from the left to the protocol name that is associated with it on the right.

Correct Answer:

Explanation:

The Real-Time Transport Protocol (RTP) is an Internet protocol standard that specifies a way for programs to manage the real-time transmission of multimedia data over either unicast or multicast network services. RTP is commonly used in Internet telephony applications. RTP does not in itself guarantee real-time delivery of multimedia data; it does, however, provide the wherewithal to manage the data as it arrives to best effect. RTP combines its data transport with a control protocol (RTCP), which makes it possible to monitor data delivery for large multicast networks. When protocols are used in conjunction, RTP is originated and received on even port numbers and the associated RTCP communication uses the next higher odd port number. Monitoring allows the receiver to detect if there is any packet loss and to compensate. The Secure Real-time Transport Protocol (or SRTP) defines a profile of RTP (Real-time Transport Protocol), intended to provide encryption, message authentication and integrity, and replay protection to the RTP data in both unicast and multicast applications. Since RTP is closely related to RTCP (Real Time Control Protocol) which can be used to control the RTP session, SRTP also has a sister protocol, called Secure RTCP (or SRTCP); SRTCP provides the same security-related features to RTCP, as the ones provided by SRTP to RTP. Utilization of SRTP or SRTCP is optional to the utilization of RTP or RTCP; but even if SRTP/SRTCP are used, all provided features (such as encryption and authentication) are optional and can be separately enabled or disabled. The only exception is the message authentication feature which is indispensably required when using SRTCP. On slow links, it may be advantageous to compress the IP/UDP/RTP headers using Compressed RTP (cRTP). If you use cRTP then the 40 bytes of overhead incurred by the IP/UDP/RTP headers can typically be compressed down to 2 to 4 bytes (2 bytes when no UDP checksums are sent, and 4 bytes when checksums are sent). Enabling compression on both ends of a low-bandwidth serial link can greatly reduce the network overhead if it carries a lot of RTP traffic. cRTP is supported on serial lines using Frame Relay, HDLC, or PPP encapsulation. It is also supported over ISDN interfaces. CRTP should not be used on links greater than 2 Mbps.

Question 11

What are the two major types of VoIP gateways?

A. E and M B. FXO and FXS C. CAS and CCS D. analog and digital

Correct Answer: D

Question 12

What is the prerequisite for configuring Cisco AutoQoS VoIP on a Cisco catalyst switch?

A. Configure trust boundaries. B. Configure the mls qos global configuration command. C. Configure Cisco Express Forwarding. D. Cisco Discovery Protocol version 2. E. Configure correct bandwidth on all interfaces.

Correct Answer: D

Question 13

In the destination patterns, which wildcard symbol indicates a single-digit placeholder?

A. % B. () C. + D. . (period)

Correct Answer: D

Question 14

What are the three appropriate DSCP-to-CoS map statements that will assign AF31 and AF32 a CoS of 3, and AF42 a CoS of 4? (Choose three.)

A. mls qos map dscp-cos 28 to 3 B. mls qos map dscp-cos 0 8 18 af31 34 46 48 56 C. mls qos map dscp-cos 36 to 4 D. mls qos map dscp-cos af31 to 3 E. mls qos map dscp-cos 0 8 16 26 34 46 48 56 F. mls qos map dscp-cos 32 to 3

Correct Answer: A,C,D

Question 15

Using the Cisco QoS baseline model, what are the PHB, DSCP, and CoS values for voice traffic, respectively?

A. EF, 42, and 3 B. EF, 46, and 5 C. AF41, 42, and 7 D. AF41, 46, and 1

Correct Answer: B

Cisco Implementing Cisco Unified Communications Voice over IP and QoS v8.0 (CVOICE v8.0) - 642-437 Exam Practice Test