CCNP Practice Question: Given the following configuration on a Cisco IOS…

Answer analysis

Option-by-option breakdown

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

• ✓

  The router will limit the transmit rate on Serial0/0/0 to an average of 1 Mbps by queuing excess packets.

  Why this is correct

  This is the definition of traffic shaping. The 'shape average 1000000' command configures a token bucket that allows bursts up to the committed burst size, but the average transmit rate is capped at 1 Mbps. When traffic exceeds this rate, excess packets are buffered in the shaping queue rather than dropped (unless the queue overflows and tail drop occurs). This smoothing of traffic avoids packet loss and is appropriate for interfaces that can tolerate delay but need to conform to a subscribed rate.

• ✗

  The router will drop any traffic exceeding 1 Mbps on Serial0/0/0.

  Why it's wrong here

  Dropping excess traffic is the behavior of traffic policing, not shaping. Policing uses a token bucket to immediately drop (or re-mark) packets that exceed the configured rate, without buffering them. In this configuration, because 'shape average' is used, excess packets are queued for later transmission, not dropped, provided the queue has available buffers. So this answer confuses policing with shaping.

• ✗

  The router will mark all traffic with a rate limit of 1 Mbps but not enforce it.

  Why it's wrong here

  This answer incorrectly suggests that the command only sets a marker or label. In reality, shaping actively enforces the rate by holding excess traffic in a queue and transmitting it later, so the average rate is enforced. Marking without enforcement would be a feature like 'police' with a 'conform-action' and 'exceed-action' that only sets a DSCP or precedence value, but even that still has an action; 'shape average' does not just mark traffic.

• ✗

  The configuration is invalid because 'shape average' requires a class-map with a match statement.

  Why it's wrong here

  This is false. The shape average command can be applied directly in policy-map class-default, which is the implicit class that matches all unclassified traffic. It does not require a named class-map with a specific match statement. In fact, applying shaping to class-default is a common approach to rate-limit all traffic on an interface without needing to classify it. The configuration is valid.