210-060 · Question #270
Which of the following statements best describes DiffServ? (Select the best answer.)
The correct answer is A. It prioritizes packets by traffic class. DiffServ (Differentiated Services) is a QoS model that classifies and prioritizes network traffic by marking packets with DSCP values and forwarding them according to predefined traffic classes.
Question
Which of the following statements best describes DiffServ? (Select the best answer.)
Options
- AIt prioritizes packets by traffic class.
- BIt is not a QoS model that is recommended by Cisco for voice traffic.
- CIt requires applications to reserve their end-to-end bandwidth requirements.
- DIt is a traffic policing mechanism for when traffic exceeds minimum bandwidth limits.
How the community answered
(69 responses)- A91% (63)
- B4% (3)
- C3% (2)
- D1% (1)
Why each option
DiffServ (Differentiated Services) is a QoS model that classifies and prioritizes network traffic by marking packets with DSCP values and forwarding them according to predefined traffic classes.
DiffServ operates by classifying packets into traffic classes and applying Per-Hop Behaviors (PHBs) such as Expedited Forwarding (EF) for voice and Assured Forwarding (AF) for other priority traffic. Each router in the path makes independent forwarding decisions based on the DSCP marking in the packet header, providing scalable QoS without requiring end-to-end signaling. Cisco strongly recommends DiffServ as the QoS model for enterprise voice and video deployments.
DiffServ is specifically recommended by Cisco for voice and video traffic due to its scalability and ability to prioritize traffic using DSCP markings.
Requiring applications to reserve end-to-end bandwidth describes IntServ (Integrated Services) using RSVP signaling, which is a fundamentally different QoS model.
Traffic policing for exceeding bandwidth thresholds is a separate QoS mechanism; DiffServ is a classification and per-hop forwarding model, not a policing construct.
Concept tested: DiffServ QoS model traffic class prioritization
Source: https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoS-SRND-Book/QoSIntro.html
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