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350-501 Automation and Quality of Services Practice Question

Which three mechanisms are used within the DiffServ model to provide QoS in an SP network? (Choose three.)

⚠ Common exam trap

Cisco often tests the distinction between the DiffServ and IntServ models, so the trap here is that candidates may confuse RSVP (IntServ) as a DiffServ mechanism, or incorrectly associate PCEP with QoS instead of its actual role in traffic engineering path computation.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Classification and marking at the edge using DSCP

In the DiffServ model, QoS is implemented by classifying and marking packets at the network edge using the DSCP field in the IP header. This marking determines how each packet is treated within the core network, enabling scalable, class-based service differentiation without per-flow state.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
End-to-end path computation via PCEP
Why it's wrong here
PCEP is for SR-TE, not part of DiffServ basics.
✓
Classification and marking at the edge using DSCP
Why this is correct
Edge devices classify and mark packets with DSCP.
✗
IntServ resource reservation via RSVP
Why it's wrong here
IntServ is a different model; DiffServ does not use per-flow reservation.
✓
Per-hop behaviors (PHB) including EF, AF, and CS
Why this is correct
PHBs define how traffic is treated at each hop.
✓
Traffic conditioning through policing and shaping
Why this is correct
Policing and shaping enforce traffic contracts.

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350-501 Automation and Quality of Services Practice Question

Why each option matters

Option-by-option breakdown

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