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QUESTION 50
Exhibit:

Study the exhibit carefully. A router has a 256 kbps Frame Relay circuit connected to interface serial 0/0. As a large FTP packet is being placed into the hardware transmit queue of interface serial 0/0, a voice packet is placed into the priority queue of that interface. How, and in what order, will the packets be transmitted?
A. The voice packet will be transmitted first, followed by the fragmented FTP packet.
B. The FTP packet will be fragmented and the voice packet will be interleaved.
C. The voice packet will be transmitted first, followed by the FTP packet in its entirety.
D. The FTP packet will be transmitted first in its entirety, followed by the voice packet.
E. None of the above.

Correct Answer: D Section: (none) Explanation
QUESTION 51
With QOS there are generally two options; the Differentiated Services model and the Integrated Services model. What are two characteristics of the DiffServ model? (Select two)
A. Traffic that is divided into classes
B. Not scalable to large implementations
C. Service guarantee
D. QoS mechanisms that are used without prior signaling
E. Applications that signal their particular QoS and bandwidth requirements

Correct Answer: AD Section: (none) Explanation
Explanation/Reference:
Explanation: The DiffServ model is similar to a concept known as “soft QoS.” With soft QoS, QoS mechanisms are used without prior signaling. In addition, QoS characteristics (for example, bandwidth and delay), are managed on a hop-by-hop basis by policies that are established independently at each intermediate device in the network. This action is also known as per-hop behavior (PHB). The soft QoS approach is not considered an end-to-end QoS strategy because end-to-end guarantees cannot be enforced. However, soft QoS is a more scalable approach to implementing QoS than hard QoS (the IntServ model), because many (hundreds or potentially thousands) of applications can be mapped into a small set of classes upon which similar sets of QoS behaviors are implemented. Although QoS mechanisms in this approach are enforced and applied on a hop-by-hop basis, uniformly applying global meaning to each traffic class provides both flexibility and scalability. With DiffServ, network traffic is divided into classes based on business requirements. Each of the classes can then be assigned a different level of service. As the packets traverse a network, each of the network devices identifies the packet class and services the packet according to that class. It is possible to choose many levels of service with
DiffServ. For example, voice traffic from IP phones is usually given preferential treatment over all other application traffic, e-mail is generally given best-effort service, and nonbusiness traffic can either be given very poor service or blocked entirely.
QUESTION 52
You need to determine the best method for implementing QoS on the Certkiller network. Which two statements are true about the various methods of implementing QoS? (Select two)
A. Cisco AutoQoS provides capabilities to automate VoIP deployments.
B. The auto qos global configuration command is used to configure Cisco AutoQoS.
C. Cisco AutoQoS can be used repeatedly to apply a single QoS policy to multiple interfaces.
D. The Modular QoS CLI (MQC) is the best way to fine tune QoS configurations.
E. The SDM QoS wizard is the fastest way to implement QoS.
F. Cisco AutoQoS includes an optional web-based GUI for automating the configuration of QoS services.

Correct Answer: AD Section: (none) Explanation
Explanation/Reference:
Explanation: Cisco introduced the Modular QoS CLI (MQC) to simplify QoS configuration by making configurations modular. With MQC, QoS can be configured in a building-block approach using a single module repeatedly to apply policy to multiple interfaces. Cisco AutoQoS represents innovative technology that simplifies the challenges of network administration by reducing QoS complexity, deployment time, and cost to enterprise networks. Cisco AutoQoS incorporates value-added intelligence in Cisco IOS software and Cisco Catalyst software to provision and assist in the management of large-scale QoS deployments. The first phase of Cisco AutoQoS VoIP offers straightforward capabilities to automate VoIP deployments for customers that want to deploy IP telephony but lack the expertise and staffing to plan and deploy IP QoS and IP services. The second phase, Cisco AutoQoS Enterprise, which is supported only on router interfaces, uses Network-Based Application Recognition (NBAR) to discover the traffic. After this discovery phase, the AutoQoS process can then configure the interface to support up to 10 traffic classes.
QUESTION 53
With QOS there are generally two options; the Differentiated Services model and the Integrated Services model. Which two statements are true about RSVP and the IntServ QoS model? (Select two)
A. The flow-based approach of RSVP is ideal for large, scalable implementations such as the public Internet.
B. RSVP specifically provides a level of service for rate-sensitive and delay-sensitive traffic.
C. RSVP is an IP protocol that uses IP protocol ID 46, and TCP/UDP ports 3455.
D. A drawback of implementing RSVP is the requirement to migrate to a supporting routing protocol.
E. RSVP is a routing protocol.
F. RSVP uses DSCP to signal QoS requirements to routers.

Correct Answer: BC Section: (none) Explanation
Explanation/Reference:
Explanation: RSVP is a network control protocol that enables applications to obtain differing QoS for their data flows. Such a capability recognizes that different applications have different network performance requirements. Some applications, including the more traditional interactive and batch applications, require reliable delivery of data but do not impose any stringent requirements for the timeliness of delivery. Newer application types, including videoconferencing, IP telephony, and other forms of multimedia communications, require almost the exact opposite: Data delivery must be timely but not necessarily reliable. Thus, RSVP was intended to provide IP networks with the ability to support the divergent performance requirements of differing application types. RSVP is an IP protocol that uses IP protocol ID 46 and TCP and UDP port 3455. It is important to note that RSVP is not a routing protocol. RSVP works in conjunction with routing protocols and installs the equivalent of dynamic access control lists (ACLs) along the routes that routing protocols calculate. Thus, implementing RSVP in an existing network does not require migration to a new routing protocol.
QUESTION 54
You need to configure QoS on a new Certkiller router. What are two steps needed to define a QoS policy for a traffic class? (Select two)
A. Assign priorities to the class.
B. Determine the interfaces in which to apply policy.
C. Determine a minimum bandwidth guarantee.
D. Configure access control lists.

Correct Answer: BC Section: (none) Explanation Explanation/Reference:
Explanation:
Complete these steps to implement QoS using the MQC:
Step 1 Configure traffic classification by using the class-map command. Step 2 Configure traffic policy by
associating the traffic class with one or more QoS

features using the policy-map command.
Step 3 Attach the traffic policy to inbound or outbound traffic on interfaces, subinterfaces, or virtual circuits
by using the service-policy command.

QUESTION 55
With QOS there are generally two options; the Differentiated Services model and the Integrated Services model. Which two statements about the DiffServ QoS model are true? (Select two)
A. Network traffic is identified by class, and the level of service is chosen for each class.
B. The DiffServ model relies on a fairly simple mechanism to provide QoS over a wide range of equipment.
C. The DiffServ model is more scalable than the IntServ model.
D. The flow-based approach of the DiffServ model is ideal for large scalable implementations such as the public Internet.
E. DiffServ requires RSVP to set up a path through the network to accommodate the requested QoS.
F. RSVP enables the DiffServ model to provide end-to-end QoS.

Correct Answer: AC Section: (none) Explanation
Explanation/Reference:
Explanation: The DiffServ model is similar to a concept known as “soft QoS.” With soft QoS, QoS mechanisms are used without prior signaling. In addition, QoS characteristics (for example, bandwidth and delay), are managed on a hop-by-hop basis by policies that are established independently at each intermediate device in the network. This action is also known as per-hop behavior (PHB). The soft QoS approach is not considered an end-to-end QoS strategy because end-to-end guarantees cannot be enforced. However, soft QoS is a more scalable approach to implementing QoS than hard QoS (the IntServ model), because many (hundreds or potentially thousands) of applications can be mapped into a small set of classes upon which similar sets of QoS behaviors are implemented. Although QoS mechanisms in this approach are enforced and applied on a hop-by-hop basis, uniformly applying global meaning to each traffic class provides both flexibility and scalability. With DiffServ, network traffic is divided into classes based on business requirements. Each of the classes can then be assigned a different level of service. As the packets traverse a network, each of the network devices identifies the packet class and services the packet according to that class. It is possible to choose many levels of service with DiffServ. For example, voice traffic from IP phones is usually given preferential treatment over all other application traffic, e-mail is generally given best-effort service, and nonbusiness traffic can either be given very poor service or blocked entirely.
QUESTION 56
Certkiller has chosen to use the DiffServ model over the IntServ model. Which two statements about the DiffServ model are true? (Select two)
A. The primary goal of DiffServ is scalability.
B. The DiffServ field occupies the same eight bits of the MAC header that were previously used for the ToS field.
C. DiffServ uses the DiffServ field in the MAC header to mark frames into behavior aggregates (BAs).
D. A class can be identified as a single application, multiple applications with similar service needs, or be based on the source or destination IP addresses.
E. A drawback of the DiffServ model is that it does not provide backward compatibility with devices that can only use the ToS field.
F. The first six high-order bits of the DiffServ field are used to identify the Resource Reservation Protocol (RSVP) value.

Correct Answer: AD Section: (none) Explanation
Explanation/Reference:
Explanation: The DiffServ model is similar to a concept known as “soft QoS.” With soft QoS, QoS mechanisms are used without prior signaling. In addition, QoS characteristics (for example, bandwidth and delay), are managed on a hop-by-hop basis by policies that are established independently at each intermediate device in the network. This action is also known as per-hop behavior (PHB). The soft QoS approach is not considered an end-to-end QoS strategy because end-to-end guarantees cannot be enforced. However, soft QoS is a more scalable approach to implementing QoS than hard QoS (the IntServ model), because many (hundreds or potentially thousands) of applications can be mapped into a small set of classes upon which similar sets of QoS behaviors are implemented. Although QoS mechanisms in this approach are enforced and applied on a hop-by-hop basis, uniformly applying global meaning to each traffic class provides both flexibility and scalability. With DiffServ, network traffic is divided into classes based on business requirements. Each of the classes can then be assigned a different level of service. As the packets traverse a network, each of the network devices identifies the packet class and services the packet according to that class. It is possible to choose many levels of service with DiffServ. For example, voice traffic from IP phones is usually given preferential treatment over all other application traffic, e-mail is generally given best-effort service, and nonbusiness traffic can either be given very poor service or blocked entirely.
QUESTION 57
With QOS there are generally two options; the Differentiated Services model and the Integrated Services model. Which two statements are true about the implementation of QoS? (Select two)
A. Implementing IntServ involves the utilization of RSVP.
B. Traffic should be classified and marked by the core network devices.
C. Implementing IntServ allows QoS to be performed by configuring only the ingress and egress devices.
D. Traffic should be classified and marked as close to the edge of the network as possible.
E. Implementing DiffServ involves the configuration of RSVP.

Correct Answer: AD Section: (none) Explanation
Explanation/Reference:
Explanation: Cisco IOS QoS features enable network administrators to control and predictably service a variety of networked applications and traffic types, allowing network managers to take advantage of a new generation of media-rich and mission-critical applications. The goal of QoS is to provide better and more predictable network service by providing dedicated bandwidth, controlled jitter and latency, and improved loss characteristics. QoS achieves these goals by providing tools for managing network congestion, shaping network traffic, using expensive wide-area links more efficiently, and setting traffic policies across the network. QoS offers intelligent network services that, when correctly applied, help to provide consistent and predictable performance Integrated Services (IntServ): IntServ can provide very high QoS to IP packets. Essentially, applications signal to the network that they will require special QoS for a period of time and that bandwidth should be reserved. With IntServ, packet delivery is guaranteed. However, the use of IntServ can severely limit the scalability of a network. IntServ uses Resource Reservation Protocol (RSVP) to explicitly signal the QoS needs of traffic of an application along the devices in the end-to-end path through the network. If network devices along the path can reserve the necessary bandwidth, the originating application can begin transmitting. If the requested reservation fails along the path, the originating application will not send any data.
QUESTION 58
The best QoS method needs to be determined for use in the Certkiller network. In which QoS model do applications signal the network that they require certain QoS parameters?
A. Best Effort
B. Hierarchical
C. DiffServ
D. IntServ
E. WFQ
F. CBWFQ
G. None of the above

Correct Answer: D Section: (none) Explanation
Explanation/Reference:
Explanation: Integrated Services (IntServ): IntServ can provide very high QoS to IP packets. Essentially, applications signal to the network that they will require special QoS for a period of time and that bandwidth should be reserved. With IntServ, packet delivery is guaranteed. However, the use of IntServ can severely limit the scalability of a network.
QUESTION 59
You need to define a new QoS policy for use in the Certkiller network. What are two steps that are needed to define a QoS policy? (Select two)
A. Configure CBWFQ for best-effort traffic.
B. Establish timers.
C. Determine a specific transfer rate.
D. Set a minimum bandwidth guarantee.
E. Set a maximum bandwidth limit.
F. Increase bandwidth.

Correct Answer: DE Section: (none) Explanation
Explanation/Reference:
Explanation: When you specify the priority command for a class, you can use the bandwidth argument to specify the maximum bandwidth in kilobits per second. You use this parameter to specify the maximum amount of bandwidth allocated for packets belonging to the class configured with the priority command. The bandwidth parameter both guarantees bandwidth to the priority class and restrains the flow of packets from the priority class.
QUESTION 60
Certkiller is contemplating the use of the IntServ model for their QoS needs. What is a drawback to using the IntServ model?
A. Admission control not supported
B. Not scalable to large implementations
C. UDP not supported
D. Use of dynamic port numbers
E. RSVP that signals QoS requests per individual flow
F. None of the above

Correct Answer: B Section: (none) Explanation Explanation/Reference:
Explanation:
IntServ also has these drawbacks:

1.
There is continuous signaling because of the stateful RSVP architecture.

2.
The flow-based approach is not scalable to large implementations, such as the public Internet, because RSVP has to track each individual flow. This circumstance would make end-to-end signaling very difficult. A possible solution is to combine IntServ with elements from the DiffServ model to provide the needed scalability.
QUESTION 61
You want to implement QoS on the Certkiller devices to support a converged network. What are the three steps to implement a QoS policy in a network? (Select three)
A. Divide traffic into classes.
B. Identify traffic requirements.
C. Label each class.
D. Define QoS policies for each class.
E. Choose DiffServ or IntServ as the QoS model.
F. Configure ACLs to define queues.

Correct Answer: ABD Section: (none) Explanation
Explanation/Reference:
Explanation:
There are three basic steps involved in implementing QoS on a Network:

1.
Identify traffic and its requirements. Study the network to determine the type of traffic running on the network and then determine the QoS requirements for the different types of traffic.

2.
Group the traffic into classes with similar QoS requirements.

3.
Define the QoS policies that will meet the QoS requirements for each traffic class.
QUESTION 62
You have been tasked with setting up QoS policies on the Certkiller network. For defining the QoS policies for each traffic class, which parameters should be identified? (Select three)
A. Priority
B. Average bandwidth guarantee
C. Maximum bandwidth guarantee
D. IP precedence
E. Minimum bandwidth guarantee
F. Optimum bandwidth guarantee

Correct Answer: ACE Section: (none) Explanation
Explanation/Reference:
Explanation:
When implementing QoS policies on network for each traffic class, you need to identify the parameters of:
priority, Maximum bandwidth, Minimum Bandwidth Guarantee.
Example:
When you specify the priority command for a class, you can use the bandwidth argument to specify the
maximum bandwidth in kilobits per second. You use this parameter to specify the maximum amount of
bandwidth allocated for packets belonging to the class configured with the priority command. The
bandwidth parameter both guarantees bandwidth to the priority class and restrains the flow of packets from
the priority class.
priority{bandwidth | percent percentage} [burst]

QUESTION 63
DRAG DROP
Drag each descriptor on the left to the QoS model on the right to which the descriptor applies.
Note: Not all descriptors will be applied.

A.
B.
C.
D.

Correct Answer: Section: (none) Explanation
Explanation/Reference:
Explanation: Integrated Services (IntServ): IntServ can provide very high QoS to IP packets. Essentially, applications signal to the network that they will require special QoS for a period of time and that bandwidth should be reserved. With IntServ, packet delivery is guaranteed. However, the use of IntServ can severely limit the scalability of a network. IntServ uses Resource Reservation Protocol (RSVP) to explicitly signal the QoS needs of traffic of an application along the devices in the end-to-end path through the network. If network devices along the path can reserve the necessary bandwidth, the originating application can begin transmitting. If the requested reservation fails along the path, the originating application will not send any data. DiffServ: The DiffServ model is similar to a concept known as “soft QoS.” With soft QoS, QoS mechanisms are used without prior signaling. In addition, QoS characteristics (for example, bandwidth and delay), are managed on a hop-by-hop basis by policies that are established independently at each intermediate device in the network. This action is also known as per-hop behavior (PHB). The soft QoS approach is not considered an end-to-end QoS strategy because end-to-end guarantees cannot be enforced. However, soft QoS is a more scalable approach to implementing QoS than hard QoS (the IntServ model), because many (hundreds or potentially thousands) of applications can be mapped into a small set of classes upon which similar sets of QoS behaviors are implemented. Although QoS mechanisms in this approach are enforced and applied on a hop-by-hop basis, uniformly applying global meaning to each traffic class provides both flexibility
and scalability. With DiffServ, network traffic is divided into classes based on business requirements. Each of the classes can then be assigned a different level of service. As the packets traverse a network, each of the network devices identifies the packet class and services the packet according to that class. It is possible to choose many levels of service with DiffServ. For example, voice traffic from IP phones is usually given preferential treatment over all other application traffic, e-mail is generally given best-effort service, and nonbusiness traffic can either be given very poor service or blocked entirely.
QUESTION 64
Which two statements about the best effort model for QoS are true? (Select two)
A. The default policy identifies a delay sensitive class, best effort class, and a default class.
B. The model provides guaranteed service.
C. Delay sensitive packets are given preferential treatment.
D. The model is still predominant on the Internet.
E. The model is highly scalable.
F. The default policy identifies a delay sensitive class and a default class.

Correct Answer: DE Section: (none) Explanation
Explanation/Reference:
Explanation: Best-effort is a single service model in which an application sends data whenever it must, in any quantity, without requesting permission or first informing the network. For best-effort service, the network delivers data if it can, without any assurance of reliability, delay bounds, or throughput. The Cisco IOS QoS feature that implements best-effort service is FIFO queuing. FIFO is the default method of queuing for LAN and high speed WAN interfaces on switches and routers. Best-effort service is suitable for a wide range of networked applications such as general file transfers, e-mail and Web browsing.

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