| ign="center"> | | | | improve |
| NCTS - Converged IP Telephony Solutions | | | | A is the correct answer. You can change the default |
| This certification validates your understanding of the | | | | MTU, if appropriate; however, reducing the MTU can |
| standards and protocols associated with planning, | | | | put more data on the WAN sooner and is not |
| designing and deploying converged IP solutions. | | | | necessarily as efficient. A trade-off exists between |
| This certification tests your knowledge and skills in the | | | | improved network performance and voice quality. |
| following areas: | | | | 26. Which echo control device has the following |
| - Major Components of VoIP | | | | characteristics?detects a signal on the incoming or |
| - VoIP Network Design Considerations | | | | outgoing pathswitches attenuation into the other path |
| - Transport and Session Layer Technologies | | | | to reduce the level of any returning signal |
| - Implementing Quality of Service | | | | 27. - A. Echo Switcher |
| - WLAN Convergence Issues | | | | 28. - B. Echo Canceller |
| - VoIP Standardization and Signaling Protocols | | | | 29. - C. Echo Eliminator |
| Exams for this Certification -- Technology Standards | | | | 30. - D. Echo Suppressor |
| and Protocols for IP Telephony Solutions 920-803 | | | | D. D is the correct answer. An echo suppressor, or |
| 920-803 Technology Standards and Protocols for IP | | | | voice switch, is a device that detects a signal on the |
| Telephony Solutions | | | | incoming or outgoing path and switches attenuation into |
| Exam Objectives: | | | | the other path to reduce the level of any returning |
| - Major Components of VoIP (18% of Exam) | | | | signal. This suppression technique can be used in |
| - VoIP Network Design Considerations (42% of Exam) | | | | speakerphones, headsets, and wireless handsets. |
| - Transport & Session Layer Technologies (12% of | | | | 31. A customer is operating in an Ethernet environment. |
| Exam) | | | | As utilization has increased, the customer has been |
| - Implementing Quality of Service (10% of Exam) | | | | experiencing unpredictable delays between packets |
| - WLAN Convergence Issues (4% of Exam) | | | | due to network collisions. |
| - VoIP Standardization & Signaling Protocols (14% of | | | | At a minimum, at which Layer should the customer |
| Exam) | | | | deploy switches at both end points to avoid collisions? |
| Sample Exam Questions: | | | | 32. - A. Layer 1 |
| | | | 33. - B. Layer 2 |
| 1. Which VoIP network component converts one | | | | 34. - C. Layer 3 |
| media stream to another and can interact with call | | | | 35. - D. Layer 4 |
| controllers, proxies, and soft switches via proprietary or | | | | D. B is the correct answer. At a minimum, Layer 2 |
| standard protocols such as SIP? | | | | switching is required at both end points to avoid |
| 2. - A. H.323 Gateway | | | | network collision. |
| 3. - B. Gatekeeper | | | | 36. A designer has selected User Datagram Protocol |
| 4. - C. Media Gateway | | | | (UDP) instead of Transmission Control Protocol (TCP) |
| 5. - D. SIP Registrar/Proxy | | | | for a VoIP application. |
| B. C is the correct answer. The Media Gateway | | | | What rationale supports this decision? |
| performs the following: 1. Converts one media stream | | | | 37. - A. the application requires flow control and error |
| to another; for example, converts voice packets to | | | | recovery |
| analog. 2. Can interact with call controllers, proxies, and | | | | 38. - B. the application requires a Layer 5 Session |
| soft switches via proprietary or standard protocols | | | | protocol |
| such as SIP. | | | | 39. - C. the application requires a Layer 4 |
| 6. Identify the VoIP system component that performs | | | | connection-oriented protocol |
| the following functions:receives call setup request | | | | 40. - D. the application has voice and multimedia traffic |
| messages.determines the status of destination devices | | | | and delay must be minimized |
| and checks the authorization of users to originate or | | | | D. D is the correct answer. UDP is well-suited to VoIP |
| receive calls. | | | | traffic, such as voice and multimedia, because it lacks |
| 7. - A. Call Server | | | | many of the features of TCP that introduce delay, |
| 8. - B. Gatekeeper | | | | such as flow control and error recovery. Rather than |
| 9. - C. Media Server | | | | retransmitting lost packets, UDP discards the packets. |
| 10. - D. SIP Proxy/Registrar | | | | 41. Select the protocol with the following |
| B. A is the correct answer. Call Server performs the | | | | characteristics:set asides the amount of bandwidth |
| following: 1. Receives call setup request messages. 2. | | | | required for a transmissionuses a routing protocol for |
| Determines the status of destination devices and | | | | decision makingworks with IPv4 and IPv6allocated on |
| checks the authorization of users to originate or | | | | a first-come, first-served basis |
| receive calls. 3. Creates and sends the necessary | | | | 42. - A. H.323 |
| messages to process the call requests. | | | | 43. - B. DiffServ |
| 11. A WAN customer has an access link between two | | | | 44. - C. RSVP |
| Private Branch Exchange (PBX) systems. The access | | | | 45. - D. 802.1p |
| link has sufficient bandwidth to support only two VoIP | | | | C. C is the correct answer. Resource ReSerVation |
| calls. When a third call is connected, voice quality of all | | | | Protocol (RSVP) reserves bandwidth and other |
| three calls is impaired. | | | | resources on RSVP-compliant routers located |
| To prevent this problem, the customer wants to | | | | throughout the network. RSVP is allocated on a |
| enable a gateway to reject traffic when a defined | | | | first-come, first-served basis and ties up the amount of |
| threshold is reached. | | | | bandwidth needed for the transmission. RSVP |
| Which feature will provide this functionality? | | | | depends on a router's routing protocol for |
| 12. - A. Gate Threshold (GT) | | | | decision-making. RSVP works with both Internet |
| 13. - B. Call Auto Limit (CAL) | | | | Protocol version 4 and Internet Protocol version 6 |
| 14. - C. Call Threshold Rejection (CTR) | | | | (IPv6), which is now included as part of IP support in |
| 15. - D. Call Admission Control (CAC) | | | | many products including the major computer operating |
| C. D is the correct answer. CAC lets a gateway or | | | | systems. |
| gatekeeper reject traffic when a defined threshold is | | | | 46. A customer has implemented a VoIP solution over |
| reached. After the call is rejected, the originating | | | | a Wireless LAN (WLAN). They are reporting that the |
| gateway must find another means of handling the call. | | | | WLAN throughput is about 50 percent of its rated |
| Several possibilities exist and most are dependent on | | | | speed. |
| the configuration of the gateway. | | | | What is the likely reason for this result? |
| 16. An engineer is designing a VoIP solution for a | | | | 47. - A. Back-off timers and ACK packets have |
| customer and has the following requirements for the | | | | added overhead to the WLAN. |
| speech CODEC:best balance of voice quality and | | | | 48. - B. Radio Frequency signals are distorted or |
| bandwidth savingsworks well in WAN applicationsnear | | | | blocked by an obstacle within the WLAN. |
| toll quality voicesilence suppression or Voice Activity | | | | 49. - C. Denial of Service (DoS) attacks have created |
| Detection (VAD) in the transmission of voice | | | | WLAN instability. |
| communications | | | | 50. - D. The WLAN is directly connected to the wired |
| Which CODEC should the engineer select to best | | | | LAN, making all ports accessible to hackers. |
| meet these requirements? | | | | C. A is the correct answer. LAN components use |
| 17. - A. G.711 | | | | positive acknowledgement (ACK) packets to confirm |
| 18. - B. G.729A/B | | | | that data arrived safely. If a sending station does not |
| 19. - C. G.726 | | | | receive an ACK for the frame it sends, it assumes |
| 20. - D. G.723.1 | | | | that the data did not arrive and sends the data again. |
| C. B is the correct answer. The G.729A/B is intended | | | | The use of back-off timers and ACK packets can |
| for low bandwidth connections, such as WAN and | | | | cause a great deal of overhead on a WLAN. This |
| provides the best balance of voice quality and | | | | process is one of the main reasons that WLANs |
| bandwidth savings. It requires less bandwidth than G.711 | | | | achieve a throughput of roughly 50 percent of their |
| and delivers near toll quality voice. Uses silence | | | | rated speed. |
| suppression or Voice Activity Detection (VAD) in the | | | | Exam4Sure provides high quality IT exam practice |
| transmission of voice communications that can further | | | | questions and answers like Cisco 351-050, 642-661 |
| reduce bandwidth requirements. | | | | and etc. |
| 21. A technician is troubleshooting a serialization delay | | | | Report this article |
| issue on a customer's WAN. To try to improve | | | | This article is free for republishing |
| network performance, the technician decides to | | | | Source: |
| reduce the Maximum Transmission Unit (MTU) size. | | | | Republish this article |
| What effect will this action have on the network? | | | | |
| 22. - A. more data will be put on the network | | | | Ask a Question About this Article |
| 23. - B. less data will be put on the network | | | | >> When words have the same middle sounds? |
| 24. - C. voice quality will improve | | | | >> Exam stress! |
| 25. - D. network performance and voice quality will | | | | |