300-420 Question #321: Real Exam Question with Answer & Explanation

Question

An engineer is designing a QoS solution for a customer. The customer's internet connection has a bandwidth of 10 Mbps. The design must ensure that traffic bursts of data do not exceed the bandwidth of the connection and that received traffic does not starve out business-critical traffic. Which solution must the engineer choose?

Options

• AConfigure the queuing default queue for shaping inbound and policing inbound.
• BConfigure the queuing default queue for shaping inbound and policing outbound.
• CConfigure the queuing default queue for shaping outbound and policing inbound.
• DConfigure the queuing default queue for shaping outbound and policing outbound.

Explanation

The engineer must configure traffic shaping for outbound traffic to prevent exceeding bandwidth and traffic policing for inbound traffic to prevent business-critical traffic from being starved.

Common mistakes.

• A. Shaping is typically applied to outbound traffic to manage egress bandwidth, not inbound traffic in this context.
• B. Shaping is typically applied to outbound traffic to manage egress bandwidth, not inbound, and policing outbound would control traffic leaving the network, not received traffic.
• D. While shaping outbound is correct for managing egress bandwidth, policing outbound would control traffic leaving the network, which does not address the issue of received (inbound) traffic starving out business-critical traffic.

Concept tested. QoS- traffic shaping vs. policing direction

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_plcshpc/configuration/xe-3s/qos-plcshpc-xe-3s-book/qos-plcshpc-oview.html

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