300-420 Question #142: Real Exam Question with Answer & Explanation

Question

An engineer must design an in-band management solution for a customer with branch sites. The solution must allow remote management of the branch sites using management protocols over an MPLS WAN. Queueing is implemented at the remote sites using these classes: - Class1 equals voice traffic - Class2 equals mission-critical traffic - Class3 equals default traffic How must the solution prioritize the management traffic over the WAN?

Options

• AMark the traffic with DSCP CS1 and map into Class2 with a minimum bandwidth assigned by
• BMark the traffic with DSCP CS6 and map into Class1 with a minimum bandwidth assigned by
• CMark the traffic with DSCP EF and map into Class1 with a minimum bandwidth assigned by
• DMark the traffic with DSCP CS2 and map into Class2 with a minimum bandwidth assigned by

Explanation

{"question_number": 9, "question": "An engineer must design an in-band management solution for a customer with branch sites...Class1=voice, Class2=mission-critical, Class3=default", "correct_answer": "D", "explanation": "Network management traffic (SSH, SNMP, syslog) is standardized at DSCP CS2 per RFC 4594 and Cisco QoS design guidelines. Class2 (mission-critical) is the appropriate queue for management traffic because it gives it priority over default traffic while keeping it below voice (Class1). A minimum bandwidth guarantee (rather than a strict-priority queue) is the correct scheduling mechanism for management traffic - it ensures a reserved share of bandwidth without risking starvation of other classes. Option A uses CS1 (Scavenger class), which is the lowest-priority marking, inappropriate for management. Option B uses CS6 (reserved for routing protocols) and maps to Class1 (voice queue), which would mix management with voice traffic. Option C uses DSCP EF (Expedited Forwarding), reserved strictly for voice/real-time traffic, and maps to the voice class - incorrect for management.", "generated_by": "claude-sonnet", "llm_judge_score": 3}

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