ACA Quality of Service & Traffic Management 2

Question 1

Which DSCP value represents Expedited Forwarding (EF), typically used for VoIP traffic?

Accepted Answer

DSCP 46

Answer

DSCP EF is encoded as decimal 46 (binary 101110) and is reserved for low-latency, low-jitter, low-loss traffic such as VoIP.

Question 2

What is the valid range of 802.1p Class of Service (CoS) values in an 802.1Q tag?

Accepted Answer

0–7

Answer

802.1p CoS uses a 3-bit Priority Code Point (PCP) field in the 802.1Q tag, providing 8 possible values from 0 to 7.

Question 3

Which queuing mechanism guarantees a minimum bandwidth to each class while still allowing unused bandwidth to be shared?

Accepted Answer

Class-Based Weighted Fair Queuing (CBWFQ)

Answer

CBWFQ assigns guaranteed minimum bandwidth to each defined class and distributes any remaining bandwidth proportionally among classes.

Question 4

What does WRED stand for and what problem does it solve?

Accepted Answer

Weighted Random Early Detection — prevents tail-drop congestion by proactively dropping packets before queues fill

Answer

WRED (Weighted Random Early Detection) randomly drops packets before queues are completely full, preventing TCP global synchronization and favoring lower-priority traffic for drops.

Question 5

In Aruba AOS-CX switches, what is the default number of QoS queues available per port?

Accepted Answer

8

Answer

Aruba AOS-CX switches support 8 egress queues per port, allowing granular traffic prioritization aligned to 802.1p CoS or DSCP values.

(ACA) Aruba Certified Associate Certification Practice Test

(ACA) Aruba Certified Associate Certification Practice Test

ACA Quality of Service & Traffic Management 2