Which Quality of Service (QoS) mechanism is used to identify traffic flow and to use DSCP, IP Precedence values, and MPLS EXP bits to create different priority levels?

Policing is a QoS mechanism that monitors traffic rates and enforces limits, typically by dropping or re-marking packets that exceed a configured threshold, rather than identifying and categorizing traffic.

Marking is the act of setting or modifying QoS values (such as DSCP or IP Precedence) within a packet header to indicate its classification, which happens after traffic has been identified.

Queueing is a congestion management technique that buffers and prioritizes packet transmission based on their assigned QoS levels, occurring after classification and marking.

Classification is the Quality of Service (QoS) mechanism responsible for identifying and categorizing specific traffic flows based on various criteria, including existing DSCP, IP Precedence values, or MPLS EXP bits, to apply appropriate priority and treatment.