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Exam : Cisco 642-845
Title : Optimizing Converged Cisco Networks


1. To have the best possible voice quality and to utilize effectively the available bandwidth, which queuing and compression mechanisms need to be used? (Choose two.)
A. class-based weighted fair queuing (CBWFQ)
B. low latency queuing (LLQ)
C. priority queuing (PQ) or custom queuing (CQ)
D. Real-Time Transport Protocol (RTP) header compression
E. TCP header compression
F. UDP header compression
Answer: BD

2. Which three statements about end-to-end delay are true? (Choose three.)
A. End-to-end delay is the sum of propagation delays, processing delays, serialization delays, and queuing delays.
B. Coast-to-coast end-to-end delay over an optical link is about 20 ms.
C. Processing delay depends on various factors, which include CPU speed, CPU utilization, IP switching mode, and router architecture.
D. Propagation and serialization delays are related to the media.
E. Propagation delay is the time it takes to transmit a packet and is measured in bits-per-second (bps).
F. Serialization delay is the time it takes for a router to take the packet from an input interface and put it into the output queue of the output interface.
Answer: ACD

3. What three statements are true about the various deployments of the 802.1x Extensible Authentication Protocol (EAP)? (Choose three.)
A. EAP-FAST has the ability to tie login with non-Microsoft user databases.
B. EAP-TLS supports static passwords.
C. PEAP supports one-time passwords.
D. LEAP does not support multiple operating systems.
E. LEAP supports Layer 3 roaming.
F. PEAP does not work with WPA.
Answer: ACE

4. What are three security problems with Wi-Fi Protected Access (WPA)? (Choose three.)
A. WPA is based on the outdated IEEE 802.11i standard.
B. WPA uses RSN, which uses the same base encryption algorithm as RC4.
C. WPA requires a hardware upgrade that may not be supported by all vendors.
D. WPA uses TKIP, which uses the same base encryption algorithm as WEP.
E. WPA is susceptible to a DoS attack when it receives two packets in quick succession with bad MICs, forcing the AP to shut down the entire Basic Service Set (BSS) for one minute.
F. WPA is susceptible to a security weakness when preshared keys are used.
Answer: DEF

5. Which two QoS statements are true about the use of the SDM QoS wizard? (Choose two.)
A. Business-critical traffic includes VoIP and voice signaling packets.
B. SDM can be used to configure a basic QoS policy for incoming traffic on WAN interfaces and IPsec tunnels.
C. SDM can provide QoS for real-time traffic and business-critical traffic.
D. SDM creates a custom-queuing (CQ) or a priority-queuing (PQ) policy.
E. SDM creates a low latency queuing (LLQ) service policy with its associated classes.
F. When allocating bandwidth, values can be entered in either bandwidth percentage or kilobytes per second (kBps).
Answer: CE

6. Which codec standard would provide the highest voice-quality, mean opinion score (MOS)?
A. G.711, PCM
B. G.728, LDCELP
C. G.729, CS-ACELP
D. G.729A, CS-ACELP
Answer: A

7. Interface congestion is causing drops in voice packets and TCP packets. The drops result in jerky speech quality and slower FTP traffic flows. Which two technologies would proactively address the TCP transfer rate and the voice problems? (Choose two.)
A. CBWFQ
B. LLQ
C. traffic shaping
D. WRED
Answer: BD

8. Voice activity detection (VAD) suppresses the transmission of silence patterns. On average, and assuming that a link carries at least 24 calls, what percentage of total bandwidth could VAD save?
A. 5
B. 15
C. 25
D. 35
E. 45
F. 55
Answer: D

9. Which two statements regarding the Wireless LAN Solution Engine (WLSE) are true? (Choose two.)
A. To support fault and policy reporting, the WLSE requires a Wireless Control System (WCS).
B. When WLSE detects an AP failure, it automatically increases the power and cell coverage of nearby APs.
C. WLSE requires the 2700 location appliance to offer location tracking.
D. WLSE can locate rogue APs and automatically shut them down.
E. WLSE configuration is done using the command line interface (CLI) or a WEB based template.
Answer: BD

10. Two sites are using a multisite centralized call processing model. The voice gateway on the remote branch has lost IP connectivity to its Cisco CallManager server. Which feature enables the remote gateway to take the role of the call agent during the WAN failure?
A. automated alternate routing (AAR)
B. Cisco CallManager Attendant Console
C. real-time protocol (RTP)
D. Survivable Remote Site Telephony (SRST)
Answer: D

11. Which two statements are true about the implementation of QoS? (Choose two.)
A. Implementing DiffServ involves the configuration of RSVP.
B. Implementing IntServ allows QoS to be performed by configuring only the ingress and egress devices.
C. Implementing IntServ involves the utilization of RSVP.
D. Traffic should be classified and marked by the core network devices.
E. Traffic should be classified and marked as close to the edge of the network as possible.
Answer: CE

12. Refer to the exhibit. Both routers have been configured as VoIP gateways. They must also support traditional telephony devices to connect to analog telephones. Which two configuration changes would correctly support the voice requirements? (Choose two.)
A. On each router, under the dial-peer voice 1 pots configuration, add the port fa0/0 command.
B. On each router, under the dial-peer voice 1 pots configuration, add the port 1/0/0 command.
C. On each router, configure dial-peer voice 1 as a voip connection and configure dial-peer voice 2 as a pots connection.
D. Under the dial-peer voice 1 pots configuration, change the destination pattern of 1111 to 2222 on the R1 router, and 2222 to 1111 on the R2 router.
E. Under the dial-peer voice 2 voip configuration, change the destination pattern of 1111 to 2222 on the R1 router, and 2222 to 1111 on the R2 router.
F. Under the dial-peer voice 2 voip configuration, change the destination target address of 10.2.2.2 to 10.1.1.1 on the R1 router, and the destination target address of 10.1.1.1 to 10.2.2.2 on the R2 router.
Answer: BE

13. Which three methods would help prevent critical network-traffic packet loss on high speed serial interfaces? (Choose three.)
A. policy routing
B. increase link capacity
C. WRED
D. CBWFQ
E. LFI
F. WFQ
Answer: BCD

14. Which two statements are true about the function of CAC? (Choose two.)
A. CAC provides guaranteed voice quality on a link.
B. CAC artificially limits the number of concurrent voice calls.
C. CAC is used to control the amount of bandwidth that is taken by a call on a link.
D. CAC prevents oversubscription of WAN resources that is caused by too much voice traffic.
E. CAC allows an unlimited number of voice calls while severely restricting, if necessary, other forms of traffic.
F. CAC solves voice congestion problems by using QoS to give priority to UDP traffic.
Answer: BD