Module 9 Pre-Assessment - QoS

Front

What is the benefit of deploying Layer 3 QoS marking across an enterprise network?

Back

Layer 3 marking can carry the QoS information end-to-end.

Answer explanation

Marking traffic at Layer 2 or Layer 3 is very important and will affect how traffic is treated in a network using QoS. Layer 2 marking of frames can be performed for non-IP traffic.Layer 2 marking of frames is the only QoS option available for switches that are not "IP aware."Layer 3 marking will carry the QoS information end-to-end.

Front

What is the function of a QoS trust boundary?

Back

A trust boundary identifies which devices trust the marking on packets that enter a network.

Answer explanation

Network traffic is classified and marked as close to the source device as possible. The trust boundary is the location where the QoS markings on a packet are trusted as they enter an enterprise network.

Front

What term describes the cause of broken conversations due to varying delays between voice packets received by an IP phone?

Back

jitter

Answer explanation

Jitter is the variation in the latency or delay of received packets. When data is sent, packets are sent in a continuous stream and are spaced evenly apart. Because of network congestion, the delay between each packet can vary instead of remaining constant.

Front

Which queuing algorithm has only a single queue and treats all packets equally?

Back

FIFO

Answer explanation

FIFO queuing sends packets out an interface in the order that they had arrived and does not make a decision about packet priority. All packets are treated equally.

Front

A network administrator is deploying QoS with the ability to provide a special queue for voice traffic so that voice traffic is forwarded before network traffic in other queues. Which queuing method would be the best choice?

Back

LLQ

Answer explanation

Low latency queuing (LLQ) allows delay-sensitive data, such as voice traffic, to be defined in a strict priority queue (PQ) and to always be sent first before any packets in any other queue are forwarded.

Front

Which type of network traffic cannot be managed using congestion avoidance tools? Options: TCP, UDP, IP, ICMP

Back

UDP

Answer explanation

Queuing and compression techniques can help to reduce and prevent UDP packet loss, but there is no congestion avoidance for User Datagram Protocol (UDP) based traffic.

Front

Why is QoS an important issue in a converged network that combines voice, video, and data communications?

Back

Voice and video communications are more sensitive to latency.

Answer explanation

Without any QoS mechanisms in place, time-sensitive packets, such as voice and video, will be dropped with the same frequency as email and web browsing traffic.

Front

What type of traffic is described as consisting of traffic that gets a lower priority if it is not mission-critical?

Back

data

Front

What type of traffic is described as predictable and smooth?

Back

voice

Front

What type of traffic is described as not resilient to loss? Options: data, video, voice

Back

video