2013 Latest CCNA Voice 640-461 Real Exam Question 131-135


Which description describes the low latency queuing algorithm?
A. Empty queue 1. If queue 1 is empty, empty queue 2, then empty queue 3, unless a packet for a higher queue arrives.
B. An administrator defines the traffic classes based on match criteria, including protocols, access control lists, and input interfaces.
C. A flow-based algorithm that simultaneously schedules interactive traffic to the front of a queue to reduce response time and fairly shares the remaining bandwidth among high-bandwidth flows.
D. This feature brings strict priority queuing to CBWFQ.
E. Packets are placed into a single queue and serviced in the order they were received.
Correct Answer: D Section: QoS Explanation
The Low Latency Queueing feature brings strict priority queueing to Class-Based Weighted Fair Queueing (CBWFQ). Strict priority queueing allows delay-sensitive data such as voice to be dequeued and sent first (before packets in other queues are dequeued), giving delay-sensitive data preferential treatment over other traffic.
Without Low Latency Queueing, CBWFQ provides weighted fair queueing based on defined classes with no strict priority queue available for real-time traffic. CBWFQ allows you to define traffic classes and then assign characteristics to that class. For example, you can designate the minimum bandwidth delivered to the class during congestion.
For CBWFQ, the weight for a packet belonging to a specific class is derived from the bandwidth you assigned to the class when you configured it. Therefore, the bandwidth assigned to the packets of a class determines the order in which packets are sent. All packets are serviced fairly based on weight; no class of packets may be granted strict priority. This scheme poses problems for voice traffic that is largely intolerant of delay, especially variation in delay. For voice traffic, variations in delay introduce irregularities of transmission manifesting as jitter in the heard conversation.
The Low Latency Queueing feature provides strict priority queueing for CBWFQ, reducing jitter in voice conversations. Configured by the priority command, Low Latency Queueing enables use of a single, strict priority queue within CBWFQ at the class level, allowing you to direct traffic belonging to a class to the CBWFQ strict priority queue. To enqueue class traffic to the strict priority queue, you configure the priority command for the class after you specify the named class within a policy map. (Classes to which the priority command is applied are considered priority classes.) Within a policy map, you can give one or more classes priority status. When multiple classes within a single policy map are configured as priority classes, all traffic from these classes is enqueued to the same, single, strict priority queue.
One of the ways in which the strict priority queueing used within CBWFQ differs from its use outside CBWFQ is in the parameters it takes. Outside CBWFQ, by using the ip rtp priority command, you specify the range of UDP ports whose voice traffic flows are to be given priority service. Using the priority command, because you can configure the priority status for a class within CBWFQ, you are no longer limited to a UDP port number to stipulate priority flows. Instead, all of the valid match criteria used to specify traffic for a class now applies to priority traffic. These methods of specifying traffic for a class include matching on access lists, protocols, and input interfaces. Moreover, within an access list you can specify that traffic matches are allowed based on the IP Differentiated Services Code Point (DSCP) value that is set using the first six bits of the Type of Service (ToS) byte in the IP header.
Although it is possible to enqueue various types of real-time traffic to the strict priority queue, we strongly recommend that you direct only voice traffic to it. This recommendation is made because voice traffic is well-behaved, whereas other types of real-time traffic are not. Moreover, voice traffic requires that delay be nonvariable in order to avoid jitter. Real-time traffic such as video could introduce variation in delay, thereby thwarting the steadiness of delay required for successful voice traffic transmission.

Which behavior can be configured with the snr calling-number local command?
A. displaying the called number instead of the remote destination at the calling party
B. displaying the original caller at the remote destination
C. displaying the enterprise directory number instead of the original caller at the calling party
D. displaying the enterprise directory number instead of the original caller at the remote destination
Correct Answer: D Section: CUCM Explanation

What application uses the Cisco Unified Operating System for administration and configuration?
A. Cisco Unity Express
B. Cisco Unified Messaging Gateway
C. Cisco Unified Communications Manager Express
D. Cisco Unified Presence
Correct Answer: D Section: Unified Presence Explanation
Cisco unity is for voice mail feature.
Cisco unified operating system is CUCM/CCME feature.

Which two types of device can the Cisco Unified Disaster Recovery use as a backup target? (Choose two.)
A. DVD ROM drive
B. FTP server
C. tape device
D. TFTP server
E. WebDAV server
F. SFTP server
Correct Answer: CF Section: CUCM Explanation
Cisco unified disaster recovery choose one of the following backup devices.
Tape Device – Stores the backup file on a locally attached tape drive Network Directory – Stores the backup file on a networked drive that is accessed through an SFTP connection

To monitor the service health and performance, which service should you activate in Cisco Unity Connection?
A. CUC Performance Service
B. CUC System Auditing
C. Real-Time Monitoring Tool
D. Cisco Serviceability Reporter
Correct Answer: D Section: Unity Connection Explanation
Activate the Cisco Serviceability Reporter service.
Link: http://www.cisco.com/en/US/docs/voice_ip_comm/connection/2x/serviceability/unified_administration/ guide/2xcucuniag100.html

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