300-420 Question #354: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An engineer must ensure that the QoS design guarantees bandwidth for the applications, and an application can request a particular type of service to support its delay requirements. Which solution must the engineer select?

Options

• ADiffserv with RSVP
• BDiffserv with DSCP
• CIntServ with DSCP
• DIntServ with RSVP

Explanation

To guarantee bandwidth for applications and allow them to request specific delay requirements, the engineer must select the IntServ QoS model with RSVP.

Common mistakes.

• A. Diffserv (Differentiated Services) is a class-based QoS model offering relative priorities, not explicit per-flow guarantees, making its combination with the IntServ-specific RSVP protocol incoherent.
• B. Diffserv with DSCP (Differentiated Services Code Point) provides class-based QoS without explicit end-to-end guarantees or mechanisms for applications to request specific service types.
• C. IntServ is associated with RSVP for signaling, not DSCP, which is the classification mechanism for the Diffserv model.

Concept tested. IntServ QoS model with RSVP

Reference. https://www.cisco.com/c/en/us/td/docs/ios/qos/configuration/guide/qos_c/qc_intgrv.html

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