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Which of the following statements best describes the characteristics of a network that is well designed for QoS?
A. Packets are classified at each router within the network. The classification is based on as many details as possible, typically using extended IP ACLs to match the packets.
B. Packets are classified based on their position from the hub and the closeness to the router. All the packets are manually classified based on their positioning and flow of the router.
C. Packets are classified based on socket address, at the router closets to the source of the traffic. The packets are characterized automatically based on flow at the routers in the middle of the network.
D. Packets are classified and marked, close to the edge of the network. The packets are treated differently based on this marking at the routers in the middle of the network.
E. Packets are classified based on variable parameters, but close to the edge of the network. The packets are automatically characterized based on flow at the routers in the middle of the network.

Correct Answer: D Section: (none) Explanation
Explanation/Reference: Explanation:
Network design practice emphasizes that you should classify or mark traffic as close to the edge of the network as possible. Traffic class is a criterion for queue selection in the various queuing schemes used at interfaces within the campus switches and WAN devices. When you connect an IP phone using a single cable, the phone becomes the edge of the managed network. As the edge device, the IP phone can and
should classify and mark traffic flows so that network QoS mechanisms can correctly handle the packets.
Reference: Arch student guide p.11-76
Which of the following would you use in the CPE to make sure that voice packets are limited to the Committed Information Rate (CIR) and do not expand beyond the CIR of Frame Relay links?
A. Prioritization
B. Traffic shaping
C. Traffic policing
D. Segmentation
E. Classification
F. Fragmentation

Correct Answer: B Section: (none) Explanation
You are a network administrator at Certkiller. Your newly appointed Certkiller trainee wants to know why CBWFQ is not recommended for voice traffic.
What will your reply be?
A. CBWFQ does not support FIFO
B. CBWFQ allows queue starvation
C. CBWFQ guarantees delay but does not guarantee bandwidth
D. CBWFQ guarantees bandwidth but does not guarantee delay
E. None of the above

Correct Answer: D Section: (none) Explanation
Within the IP header, which fields of the ToS byte provide Layer 3 classification? (Choose two.)
A. CoS
E. IP Precedence

Correct Answer: DE Section: (none) Explanation
Which of the following represent the advantages of implementing QoS in Enterprise Networks? (Choose two.)
A. It decreases propagation delay
B. It provides predictable response times.
C. It supports dedicated bandwidth per application.
D. It prevents the need to increase bandwidth when adding applications.

Correct Answer: BC Section: (none) Explanation
With regard to classification and marketing, which of the following statement is true?
A. When classifying packets at Layer 3, only Layer 3 IP Precedence markings can be used.
B. Marking features allows a router to mark any field that the classification features can examine
C. Classification features can examine different fields inside a frame or packet, unless the packet has already been marked, in which case only the marked field can be examined
D. Although classification can examine different fields inside a frame or packet, it is useful to mark the packet, so that switches and routers that later receive the packet can apply features based on the market field.

Correct Answer: D Section: (none) Explanation
Explanation/Reference: Explanation:
Packet classification features provide the capability to partition network traffic into multiple priority levels or classes of service. For example, by using the three precedence bits in the type of service (ToS) field of the IP packet header (two of the values are reserved for other purposes), you can categorize packets into a limited set of up to six traffic classes. After you classify packets, you can utilize other QoS features to assign the appropriate traffic handling policies, including congestion management, bandwidth allocation, and delay bounds for each traffic class.
Reference: ARCH student guide p.7-18.
Certkiller, the CEO of Toronto division of, want to know what the characteristics of RSVP are.
What should you tell Mrs. Bill?
A. RSVP itself provides bandwidth and delay guarantees
B. For RSVP to be end-to-end, all devices must support RSVP
C. RSVP reservations are maintained by a centralized reservations server.
D. An RSVP compatible QoS mechanism must be used to implement guarantees according to RSVP reservations.

Correct Answer: BD Section: (none) Explanation
Explanation/Reference: Explanation:
Resource Reservation Protocol. Protocol that supports the reservation of resources across an IP network.
Applications running on IP end systems can use RSVP to indicate to other nodes the nature (bandwidth,
jitter, maximum burst, and so on) of the packet streams they want to receive. Also known as Resource
Reservation Setup Protocol.
Resource Reservation Protocol (RSVP) is an IETF-draft networking protocol dedicated to being the
facilitator and carrier of standardized QOS information and parameters.

RSVP carries generic (industry-defined) QOS parameters from end nodes (inclusive) to each QOS-aware
network device included in the path between RSVP session members.
That is, RSVP is a means by which end nodes and network devices can communicate and negotiate QOS

parameters and network usage admission.
Reference: Arch student guide p. B-23.
Which two of the following factors are typically used to determine QoS requirements for real-time applications such as IP Telephony?
A. Latency
B. Jitter
C. Echo delay
D. Two-way latency
E. Propagation delay

Correct Answer: AB Section: (none) Explanation
Explanation/Reference: Explanation:
Voice, as a class of IP network traffic, has strict requirements concerning delay and delay variation (also known as jitter). Compared to most data, it is relatively tolerant of loss. To meet the requirements for voice traffic, the Cisco AVVID IP telephony solution uses a wide range of IP QoS features such as classification, queuing, congestion detection, traffic shaping, and compression.
Reference: Arch student guide p.11-76.
Which speed links is recommended for link efficiency tools to be used?
A. Links below 10 Mbps
B. Links above 2.0 Mbps
C. Links equal to 1.5 Mbps
D. Links at or below 768 Kbps

Correct Answer: D Section: (none) Explanation
Explanation/Reference: Explanation:
Link efficiency interleaving is used on links at or below 768 Kbps.
Reference: Arch student guide p.7-29
The ITU G.114 recommendation specifies which end-to-end delay as the threshold for high-quality voice.
A. 125 ms
B. 150 ms
C. 200 ms
D. 250 ms

Correct Answer: B Section: (none) Explanation
Explanation/Reference: Explanation:
When addressing the QoS needs of voice traffic, keep in mind.
1) One-way latency should be no more than 150-200 ms.
2) Jitter should be no more than 30 ms.
3) Loss should be no more than one percent.

Reference: Arch student guide p.7-45

What can be done when voice frames are delayed by large numbers of data packets at an interface?
A. Implement random early detection.
B. Implement prioritized queue service.
C. Implement aggressive fragmentation.
D. Implement token-bucket prioritization.

Correct Answer: B Section: (none) Explanation
Explanation/Reference: Explanation:
Allow applications to reserve bandwidth to meet their requirements. For example, a Voice over IP (VoIP) applications can reserve 32 kbps end-to-end using this kind of service. Cisco IOS QoS uses weighted fair queueing (WFQ) with RSVP to provide this kind of service. Guaranteed rate service is implemented using a queue-service discipline.
Reference: Arch student guide p.7-12
Which IOS QoS enhancement was created to address scalability and bandwidth guarantee issues?
A. DiffServ
B. IntServ

Correct Answer: C Section: (none) Explanation
DiffServ and IntServ are not IOS enhancements, but models of QoS implementations. WFQ is a basic queueing mechanism.

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