Full form: Quality of Service
Also known as: Quality of Service
Quick Definition
Mechanisms that prioritise certain types of network traffic to guarantee performance.
QoS is a set of techniques used to manage bandwidth, delay, jitter, and packet loss for different types of traffic. Traffic is classified (identified), marked (given a priority value), and then policed or queued according to policy. Voice (VoIP) and video traffic require low latency and jitter, while bulk data transfers can tolerate delay. QoS ensures critical applications get the resources they need even during congestion.
QoS is needed at congestion points — where traffic demand exceeds available bandwidth. Simply adding bandwidth may not solve QoS issues on shared WAN links. The CCNA exam focuses on classification (matching traffic), marking (DSCP/CoS), and queuing concepts.
QoS is a set of techniques used to manage bandwidth, delay, jitter, and packet loss for different types of traffic. Traffic is classified (identified), marked (given a priority value), and then policed or queued according to policy. Voice (VoIP) and video traffic require low latency and jitter, while bulk data transfers can tolerate delay. QoS ensures critical applications get the resources they need even during congestion.
QoS is needed at congestion points — where traffic demand exceeds available bandwidth. Simply adding bandwidth may not solve QoS issues on shared WAN links. The CCNA exam focuses on classification (matching traffic), marking (DSCP/CoS), and queuing concepts.
QoS falls under the IP Services domain of the 200-301 exam. Understanding it in context with related terms like dscp and cos is essential for answering scenario-based questions correctly.