江浙沪招生考试网

　　1.In T1 CAS, where are the signaling states and control features carried for Super Frame robbed-bit signaling?

　　A. 6th and 12th frame

　　B. 6th, 12th, 18th, and 24th frame

　　C. the first and seventeenth time slot

　　D. the first and sixteenth time slot

　　Answer: A

　　2.You are meeting with a customer that has deployed IP telephony at their headquarters location. They would like

　　to roll out IP telephony to their regional office as well. They are now using the G.711 codec at headquarters. They

　　want to be able to maximize the number of calls carried without impacting voice quality or forcing a WAN

　　upgrade. Which codec would be appropriate for their WAN?

　　A. G.726

　　B. G.723.1

　　C. G.711

　　D. G.729B

　　Answer: D

　　3.You have been forwarded some questions by a prospective VoIP customer who would like to know the Cisco

　　default sample size for the G.729 codec. What is it?

　　A. 40 ms

　　B. 30 ms

　　C. 20 ms

　　D. 10 ms

　　Answer: C

　　4.Examine the following PBX system parameters:

　　The calling side seizes the line by going off-hook on its E-lead and sends information as DTMF digits.

　　The voice path is 4-wires, and the voice enabled router is in another building from the PBX.

　　Select the correct set of commands to allow communication between a voice enabled router and a PBX.

　　A. voice port 1/0/0

　　signal immediate-start

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　　operation 4-wire

　　type 2

　　B. voice-port 1/0/0

　　signal delay-dial

　　operation 4-wire

　　type 1

　　C. voice port 1/0/0

　　signal wink-start

　　operation 4-wire

　　type 3

　　D. voice port 1/0/0

　　signal immediate-start

　　operation 4-wire

　　type 4

　　Answer: A

　　5.Examine the example output.

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　　Choose the command that will restore communication with gatekeeper functionality to this device.

　　A. h323-gateway voip h323-id GK1

　　B. gateway

　　C. h323-gateway voip bind srcaddr 172.16.2.2

　　D. h323-gateway voip GW1-zone2.abc.com abc.com ipaddr 172.16.2.1

　　Answer: B

　　6.Examine the output.

　　Your customer has sent you their MGCP gateway configuration. They are unable to get the gateway to

　　communicate with the call agent. What command needs to be inserted to resolve the problem?

　　A. ccm-manager mgcp 172.16.1.1

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　　B. mgcp call-agent 172.16.1.1

　　C. application MGCPAPP 172.16.1.1

　　D. mgcp 5036 172.16.1.1

　　Answer: B

　　7.Which command parameter specifies that the router should not attempt to initiate a trunk connection but should

　　wait for an incoming call before establishing the trunk?

　　A. codec clear-channel

　　B. connection-trunk 404555.... answer-mode

　　C. voice-port 1/0:1

　　D. ds0-group timeslots 1-23 type ext-sig

　　Answer: B

　　8.In a VoIP environment when speech samples are framed every 20 ms, a payload of 20 bytes is generated.

　　Assuming a total packet length of 60 bytes, what is the length of the packet header if cRTP is deployed without

　　redundancy checks?

　　A. 1 byte

　　B. 2 bytes

　　C. 3 bytes

　　D. 4 bytes

　　E. 20 bytes

　　F. 40 bytes

　　Answer: B

　　9.In a VoIP environment when speech samples are framed every 20 ms, a payload of 20 bytes is generated. What

　　is the size of the combined IP, UDP, and RTP headers?

　　A. 40 bytes

　　B. 12 bytes

　　C. 20 bytes

　　D. 8 bytes

　　E. 4 bytes

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　　F. 2 bytes

　　Answer: A

　　10. A customer would like to be able to retire their existing permanent PSTN trunk connection between their

　　PBXs and migrate to permanent connections over the IP WAN. There is one configuration statement missing from

　　each router in the figure. What are the two missing statements? (Choose two.)

　　A. connection tie-line e&m

　　B. connection trunk 4045551200

　　C. connection tie-line 2015551000

　　D. connection trunk 2015551000

　　E. connection tie-line 4045551200

　　F. connection tie-line

　　Answer: BD

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　　11. Your customer has forwarded this diagram and configuration. The customer wishes to have a connection

　　between its PBXs, a connection that is created and dropped as required. There is one configuration statement

　　missing from each router. What are the two missing statements? (Choose two.)

　　A. connection trunk 2015551000404555....

　　B. connection trunk 4045551200

　　C. connection tie-line 4045551200

　　D. connection tie-line 404555....

　　E. connection tie-line 2015551000

　　F. connection trunk

　　Answer: CE

　　12. You are working with a potential customer that would like to integrate its existing PBX telephone system into

　　its IP network. The accompanying figure shows that the customer has two offices that need to be connected to the

　　IP network so that the customer can exchange telephone calls without using the PSTN. Both PBXs use a

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　　proprietary signaling type.

　　Which signaling type will allow you to support your customer?

　　A. E&M

　　B. CCS

　　C. CAS

　　D. T-CCS

　　E. FXO

　　F. FXS

　　Answer: D

　　13.You have a customer that is interested in determining the number of VoIP calls their Frame Relay WAN links

　　can support. Each of their Frame Relay WAN links has 84 kbps of bandwidth available outside all other

　　applications and overhead. How many G.729 calls using the 8 kbps codec and 20 byte sample size can be

　　supported?

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　　A. 1

　　B. 2

　　C. 3

　　D. 4

　　Answer: C

　　14. You are working with a potential customer that would like to integrate its existing PBX telephone system into

　　its IP network. The accompanying figure shows that the customer has two offices that need to be connected to the

　　IP network so that the customer can exchange telephone calls without using the PSTN. Both PBXs use an in-band

　　signaling type.

　　Which signaling type will allow you to support your customer?

　　A. QSIG

　　B. CCS

　　C. CAS

　　D. T-CCS

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　　E. E&M

　　F. FXO

　　Answer: C

　　15. You are working with a potential customer that would like to integrate its existing PBX telephone system into

　　its IP network. The accompanying figure shows that the customer has two offices that need to be connected to the

　　IP network so that the customer can exchange telephone calls without using the PSTN. Both PBXs are currently

　　connected to T1 ISDN circuits.

　　Which signaling type will allow you to support your customer?

　　A. QSIG

　　B. CCS

　　C. CAS

　　D. T-CCS

　　E. E&M

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　　F. FXO

　　Answer: A

　　16. You are working with your customer in their lab to test the effect of jitter on voice quality. You have set the

　　maximum playout delay to 40 ms on the voice enabled routers. What will be the impact on voice quality if after

　　severe congestion the playout buffer empties and the source sends packets to the buffer faster than they are

　　leaving?

　　A. There will be no noticeable drop in quality.

　　B. The jitter buffer will adapt to the faster-arriving packets by expanding the buffer size.

　　C. The jitter buffer will speed up delivery of packets to the DSP so that packets are not dropped.

　　D. After the jitter buffer fills up, subsequent packets are discarded.

　　Answer: D

　　17.

　　You are working with a potential customer that would like to integrate its existing PBX telephone system into its

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　　IP network. The accompanying figure shows that the customer has two offices that need to be connected to the IP

　　network so that the customer can exchange telephone calls without using the PSTN. Both PBXs use Wink-Start

　　signaling.

　　Which signaling type will allow you to support the customer?

　　A. QSIG

　　B. CCS

　　C. CAS

　　D. T-CCS

　　E. E&M

　　F. FXO

　　Answer: E

　　18. Use the figure to answer this item.

　　Which command allows the two PBXs to use the D-channel for proprietary signaling?

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　　A. codec clear-channel

　　B. connection-trunk 404555.... answer-mode

　　C. voice-port 1/0:1

　　D. ds0-group timeslots 1-24 type ext-sig

　　Answer: D

　　19. Given the SIP network shown in the diagram, identify which two actions are initiated by the UAS (user agent

　　server)? (Choose two.)

　　A. contacts the user when a SIP invitation is received

　　B. originates the ACK method to indicate that it has received a response to an invitation

　　C. originates the BYE method to initiate call termination

　　D. originates the INVITE method including a description of the session parameters

　　E. returns a response on behalf of the user to the invitation originator

　　Answer: AE

　　20. When the Cisco IOS Packet Loss Concealment (PLC) service is being used, how many consecutive packets

　　can be lost while still maintaining an audio quality that appears to have no packets lost?

　　A. 1

　　B. 2

　　C. 3

　　D. 4

　　Answer: A

　　21. In the VoIP network above, which protocol provides the necessary sequence numbers so voice packets

　　originating at R1 are played in the correct order at R5?

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　　A. UDP

　　B. TCP

　　C. RTCP

　　D. RTP

　　E. CRTP

　　Answer: D

　　22.A network has the following characteristics:

　　What minimum WAN bandwidth would be required to support three simultaneous VoIP calls?

　　A. 247200 bps

　　B. 19200 bps

　　C. 79200 bps

　　D. 51600 bps

　　Answer: A

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　　23. In the above VoIP network, which protocol is used for multiplexing and checksum services?

　　A. UDP

　　B. TCP

　　C. RTCP

　　D. RTP

　　E. CRTP

　　Answer: A

　　24.You have designed a complex dial plan using digit manipulation. Given the following snippet of your

　　configuration file, what action would you expect to result when a call beginning with the digits "612" is received?

　　A. A nine digit number beginning with 5501 will be forwarded.

　　B. A ten digit number beginning with 5501 will be forwarded.

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　　C. A twelve digit number beginning with 5501612 will be forwarded.

　　D. A thirteen digit number beginning with 5501612 will be forwarded.

　　Answer: C

　　25.You have set up a complex dial plan using translation rules. The following translation rule has been configured.

　　What output would correspond to the test translation-rule command?

　　A. test translation-rule 1 512

　　The replaced number: 21555021512

　　B. test translation-rule 1 555

　　The replaced number: 55521555021

　　C. test translation-rule 1 617

　　The replaced number: 61721555021

　　D. test translation-rule 1 910

　　The replaced number: 21555021910

　　Answer: A

　　26.Which two codes together make up the number that follows the E.164 recommendation numbering scheme?

　　(Choose two.)

　　A. country code

　　B. subscriber code

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　　C. national destination code

　　D. provider code

　　Answer: AB

　　27.Which ITU standard number is assigned to standard PCM voice encoding?

　　A. G.711

　　B. G.723

　　C. G.726

　　D. G.729a

　　Answer: A

　　28.Which statement is true about only out-of-band signaling?

　　A. A signaling bit is robbed from each frame.

　　B. Signaling bits are sent in a special order in a dedicated signaling frame.

　　C. All signaling is directly associated with its corresponding voice frame.

　　D. All voice packets carry their own signaling.

　　Answer: B

　　29.Site A uses three-digit internal numbers and Site B uses four-digit internal numbers. All calls to the PSTN are

　　routed through SiteB. What dial plan below best represents provision simplicity?

　　A. Translate all called numbers within Site A to four digits.

　　B. Translate all called numbers within Site B to three digits.

　　C. Translate all called numbers leaving Site A to ten digits.

　　D. Translate all called numbers at either site to ten digits.

　　Answer: C

　　30.Which statement is true about VoIP packet loss?

　　A. Lost packets are simply retransmitted.

　　B. Even minimal packet loss causes echo.

　　C. IP phones can reconstruct up to three consecutive lost packets.

　　D. Codec algorithms can overcome minimal packet loss.

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　　Answer: D

　　31.What causes a VoIP call to experience missing sounds?

　　A. propagation delay

　　B. packet loss

　　C. impedance mismatch

　　D. excessive delay

　　Answer: B

　　32.What does a gateway router match to a dialed number when setting up a VoIP call?

　　A. IP route

　　B. destination pattern

　　C. call leg

　　D. session target

　　Answer: B

　　33.Which is the best way to achieve a scalable dial plan?

　　A. group numbers for a particular area

　　B. variable number of extension digits

　　C. single number prefixing

　　D. hunt groups

　　Answer: A

　　34.In T1 CAS how is hook status (on/off) relayed?

　　A. sending a special signaling packet for each channel

　　B. setting a particular bit in each channel

　　C. providing a special field in each packet header

　　D. setting a particular bit in the signaling channel

　　Answer: B

　　35.In E1 CAS, how is hook status (on/off) relayed?

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　　A. sending a special signaling packet for each channel

　　B. setting a particular bit in each channel

　　C. providing a special field in each packet header

　　D. setting a particular bit in the signaling channel

　　Answer: D

　　36.The D channel in ISDN is an example of which two signaling methods? (Choose two.)

　　A. CCS signaling

　　B. out-of-band signaling

　　C. in-band signaling

　　D. CAS signaling

　　Answer: AB

　　37.In North America, which E&M signaling type is used most often for geographically separated equipment?

　　A. Type I

　　B. Type II

　　C. Type III

　　D. Type IV

　　E. Type V

　　Answer: B

　　38.What is the most common E&M type used outside North America?

　　A. Type I

　　B. Type II

　　C. Type III

　　D. Type IV

　　E. Type V

　　Answer: E

　　39.What are two basic parameters needed to setup a dial peer connected to the PSTN? (Choose two.)

　　A. voice port

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　　B. signaling type

　　C. interface bandwidth

　　D. destination pattern

　　Answer: AD

　　40.Which command sets parameters to search a series of dial peers for a destination that is not in use?

　　A. dial-peer rotary

　　B. dial-peer circulate

　　C. dial-peer hunt

　　D. dial-peer distribute

　　Answer: C

　　41.Which preference key word assigns top precedence to a dial peer in a hunt-group?

　　A. 0

　　B. priority

　　C. 1

　　D. high

　　Answer: A

　　42.A particular set of H.323 endpoints cannot resolve the IP address of destination endpoints. What is the H.323

　　approved method to fix this problem?

　　A. Build route tables in gateways on the segment.

　　B. Hard code all IP addresses.

　　C. Introduce a gatekeeper on the segment.

　　D. Choose another signaling protocol.

　　Answer: C

　　43.Which three are supervisory signals? (Choose three.)

　　A. busy

　　B. on hook

　　C. off hook

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　　D. call waiting

　　E. ring

　　Answer: BCE

　　44.Which type of signaling is DTMF?

　　A. supervisory

　　B. route

　　C. informational

　　D. address

　　Answer: D

　　45.Which gateway interface connects to the standard station port of a PBX?

　　A. FXS

　　B. E&M

　　C. POTS

　　D. FXO

　　Answer: D

　　46.How is CAS different on E1 and T1?

　　A. T1 has more signaling channels.

　　B. E1 CAS signaling is out-of-band while T1 is in-band.

　　C. E1 uses robbed-bit signaling.

　　D. T1 uses the D channel for CAS signaling.

　　Answer: B

　　47.In the connection between a Cisco router and an E&M port on a PBX, which side is generally the Cisco side?

　　A. loop start

　　B. trunk circuit

　　C. switch port

　　D. signaling unit

　　Answer: D

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　　48.How does RTP help smooth packet delivery?

　　A. reduces packet size

　　B. marks voice packets for expedited forwarding

　　C. time-stamps packets for reordering

　　D. requests packet retransmission

　　Answer: C

　　49.What is the purpose of RTCP?

　　A. provides monitoring and control for RTP flows

　　B. provides RTP header compression

　　C. passes RTP route status information

　　D. provides RTP with packet retransmission

　　Answer: A

　　50.Which device is used to allow an H.323 stream to transit a firewall?

　　A. gatekeeper

　　B. gateway

　　C. proxy

　　D. MCU

　　Answer: C

　　51.What are the three components in an MGCP environment? (Choose three.)

　　A. gateway

　　B. gatekeeper

　　C. endpoint

　　D. call agent

　　E. proxy server

　　Answer: ACD

　　52.Which statement is true about MGCP?

　　A. Call completion is always shared, with some intelligence on the endpoint, some on the call agent.

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　　B. Endpoints always take all actions to complete calls.

　　C. Endpoints may act alone or cooperate with call agent to complete calls.

　　D. Call agents order and direct each step of call completion for the endpoints.

　　Answer: D

　　53.What is the function of a SIP registrar server?

　　A. resolves active endpoint addresses

　　B. routes service requests

　　C. acquires endpoint addresses

　　D. resolves text addresses to IP addresses

　　Answer: C

　　54.What is the function of a SIP location server?

　　A. resolves active endpoint addresses

　　B. routes service requests

　　C. acquires active endpoint addresses

　　D. resolves text addresses to IP addresses

　　Answer: A

　　55.What is the approximate frequency range of human speech?

　　A. 20 Hz to 20,000 Hz

　　B. 40 Hz to 15,000 Hz

　　C. 200 Hz to 9000 Hz

　　D. 600 Hz to 5400 Hz

　　Answer: C

　　56.What is the process of assigning audio amplitude to a unique digital code word?

　　A. linear prediction

　　B. encoding

　　C. sampling

　　D. quantization

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　　Answer: D

　　57.Which problem does a-law and mu-law address?

　　A. quantization produces distortion at higher frequencies

　　B. encoding loses signal integrity at lower frequencies

　　C. quantization produces higher signal-to-noise ratios at smaller amplitudes

　　D. encoding produces greater signal loss at higher amplitude

　　Answer: C

　　58.Which type of delay is caused when large data packets block voice packets from the outbound interface?

　　A. queuing delay

　　B. serialization delay

　　C. propagation delay

　　D. packetization delay

　　Answer: A

　　59.A 9 digit number must be dialed to reach numbers on the PSTN. What process makes sure that the first digit 9

　　is not transmitted as part of the called number?

　　A. digit alternating

　　B. digit masking

　　C. digit manipulation

　　D. digit seizing

　　Answer: C

　　60.Which process changes an internal extension into a fully qualified external PSTN number before matching to a

　　dial peer?

　　A. digit masking

　　B. forward digits

　　C. number expansion

　　D. prefix extension

　　Answer: C