mediumMultiple Choice
CCNP Practice Question: Consider the following configuration on a Cisco…
Consider the following configuration on a Cisco router:
class-map match-any CRITICAL_DATA match ip dscp af21 af22 af23
policy-map QOS
class CRITICAL_DATA
bandwidth remaining percent 50
class class-default
fair-queue
interface GigabitEthernet0/0
service-policy output QOS
Which statement about this configuration is true?
⚠ Common exam trap
Cisco often tests the distinction between 'match-any' and 'match-all' in class-maps, where candidates mistakenly think 'match-any' requires all conditions to be true, when in fact it matches if any one condition is true.
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
✓
Traffic matching DSCP AF21, AF22, or AF23 is guaranteed 50% of the interface bandwidth, and all other traffic is subject to fair-queuing.
The 'bandwidth remaining percent 50' command under class CRITICAL_DATA guarantees that traffic matching DSCP AF21, AF22, or AF23 will receive 50% of any remaining bandwidth after any explicit bandwidth reservations are satisfied. The 'class-default' uses fair-queuing, which distributes the remaining bandwidth equally among flows in that class. Since no explicit bandwidth is reserved elsewhere, the CRITICAL_DATA class effectively gets 50% of the interface bandwidth, and all other traffic is subject to fair-queuing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Traffic matching DSCP AF21, AF22, or AF23 is guaranteed 50% of the interface bandwidth, and all other traffic is subject to fair-queuing.
Why this is correct
Because the class map uses match-any, traffic marked with DSCP AF21, AF22, or AF23 is all placed into this class. The 'bandwidth remaining percent 50' command reserves half of the interface's available non-priority bandwidth for that class, and since no priority queue is configured, this effectively gives those AF flows a 50% share of the link when congestion occurs. Traffic that does not match any listed DSCP value falls into the implicit class-default, which is explicitly configured with fair-queue, so all other flows share the remaining 50% fairly.
- ✗
Only traffic with DSCP AF21 is matched; AF22 and AF23 are ignored because 'match-any' requires all conditions to be true.
Why it's wrong here
The statement is false because 'match-any' configures a logical OR, not AND: a packet needs only one of the listed DSCP values to be placed in the class. AF21, AF22, and AF23 are independent markers, yet all match the same class map. 'match-all' would require every condition to be true, but that would be impossible here because a single packet cannot carry multiple DSCP values simultaneously.
- ✗
The configuration is invalid because 'bandwidth remaining percent' cannot be used with 'fair-queue' in the same policy-map.
Why it's wrong here
This policy-map is valid because 'bandwidth remaining percent' and 'fair-queue' are applied to different classes: the former to the user-defined AF class, and the latter to the implicit class-default. Cisco's MQC permits one class to use bandwidth remaining percent while another uses fair-queue; these commands become mutually exclusive only when they are configured inside the same class. In fact, fair-queue operates on the bandwidth share not reserved by other classes, so the two features complement each other correctly.
- ✗
The policy-map will only be applied to incoming traffic on GigabitEthernet0/0.
Why it's wrong here
The 'service-policy output' statement attaches the policy to the interface's egress path, so it applies only to traffic leaving the router through GigabitEthernet0/0. To apply a policy to incoming traffic, the command would be 'service-policy input' or 'service-policy' with the direction explicitly set to 'in'. Therefore, the policy does not inspect inbound frames on that interface; directionality is a fundamental part of MQC policy attachment.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.