How do CAC and QoS differ in purpose?

• A. CAC prioritizes packets; QoS limits calls.
• B. CAC monitors only voice; QoS monitors data.
• C. CAC ensures security; QoS ensures reliability.
• D. CAC limits calls to protect bandwidth; QoS prioritizes packets.

Answer: (D)

Call Admission Control focuses on whether there is enough network capacity to support a new call; if not, it blocks or delays the setup to protect ongoing calls. Quality of Service is about how the traffic that is allowed to flow is treated—classifying, marking, and prioritizing packets, and allocating resources to meet performance targets like low latency and low jitter for voice. So CAC limits calls to preserve bandwidth, while QoS prioritizes and manages traffic to ensure quality once calls are admitted.