Which of the following are examples of metrics for QoS?

Question

Options

• ASignal degradation, attenuation, line loss
• BLatency, FIFO, WRED
• CDelay, jitter, packet loss
• DSNR, queue depth, latency
• EAttenuation, dispersion, latency

• A
  6% (2)
• C
  90% (28)
• D
  3% (1)

Explanation

Delay, jitter, and packet loss (C) are the three canonical QoS metrics because they directly measure the experience of real-time traffic - how long data takes to arrive (delay), how inconsistent that timing is (jitter), and how much data is dropped in transit (packet loss).

Why the distractors are wrong:

• A - Signal degradation, attenuation, and line loss are physical layer signal quality measurements, not QoS metrics.
• B - FIFO and WRED are queuing mechanisms used to implement QoS, not metrics that measure it.
• D - SNR (Signal-to-Noise Ratio) and queue depth are diagnostic/physical measurements; only latency belongs in the QoS metric category, making this a mixed bag.
• E - Attenuation and dispersion are again Layer 1 physical phenomena; latency alone doesn't make the set valid as QoS metrics.

Memory tip: Think of QoS metrics as what a phone call cares about - did it arrive on time (delay), was it smooth (jitter), and did any words get cut off (packet loss)? If the answer describes how the wire behaves rather than how the traffic behaves, it's not a QoS metric.

No community discussion yet for this question.