Which security service enables a network administrator to assign levels of service to a particular user?

• A. CoS
• B. ACL
• C. Encryption
• D. AAA

Answer: (A)

Assigning levels of service to a user is about tagging that user’s traffic so the network can treat it with a chosen priority. Class of Service is the mechanism used to mark frames with a priority level (often via 802.1p tags or DSCP values) so switches and routers know which packets should go into high-, medium-, or low-priority queues. Once traffic is labeled, devices can place it into the appropriate queue, allocate bandwidth, and minimize delay for the higher-priority class. This lets a network administrator ensure that a particular user’s traffic receives the desired level of service relative to others.

Other options don’t directly implement this per-user prioritization. An ACL controls access to resources rather than performance tiers. Encryption protects confidentiality and has no role in prioritizing traffic. AAA handles authentication, authorization, and accounting; it can influence policy decisions, but the actual mechanism that assigns and enforces different service levels on traffic is the CoS marking and the resulting QoS processing.