20+ practice questions focused on Qos — one of the most tested topics on the ENCOR 350-401 exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Qos PracticeDrag and drop the steps of BGP graceful restart negotiation steps into the correct order, from first to last.
Explanation: Graceful restart begins with the restarting router sending an OPEN message with the graceful restart capability, followed by the peer acknowledging, then the restarting router marking routes as stale, and finally the peer sending End-of-RIB markers.
A network engineer is implementing QoS on a WAN link to prioritize voice traffic. Which queuing mechanism provides the lowest latency for real-time traffic?
Explanation: LLQ is correct because it combines strict priority queuing with CBWFQ, ensuring that voice traffic (marked with EF or CS5) is dequeued before any other traffic class. This strict priority mechanism guarantees the lowest possible latency for real-time traffic, as packets in the priority queue are always transmitted first, regardless of congestion on the WAN link.
An engineer is configuring QoS on a Cisco ASR 1000 router to support three traffic classes: voice (EF), video (AF41), and data (default). The link is a 50 Mbps Ethernet circuit. The engineer wants to guarantee 10 Mbps for voice, 20 Mbps for video, and the remaining for data. The current policy uses bandwidth percent statements. During congestion, voice traffic is not receiving its guaranteed bandwidth. What is the most likely cause?
Explanation: The bandwidth percent command allocates a percentage of the interface bandwidth, which by default is derived from the physical interface speed. On a Cisco ASR 1000, if the interface bandwidth is not manually set to 50000 kbps, the router may use a different default value (e.g., 1000000 kbps for Ethernet), causing the bandwidth percent to allocate a much larger absolute amount than intended. This leads to incorrect bandwidth guarantees, such as voice not receiving its required 10 Mbps during congestion.
A network engineer is deploying QoS on a Cisco Catalyst 4500 switch to support four queues per port. The engineer wants to assign voice traffic to queue 1 (priority), video to queue 2, critical data to queue 3, and best-effort to queue 4. The switch is configured with the default CoS-to-queue mapping. However, video traffic is being placed in queue 1 along with voice. What should the engineer do to separate them?
Explanation: The default CoS-to-queue mapping on Cisco Catalyst 4500 switches maps CoS 5 (voice) to queue 1 (priority queue) and CoS 4 (video) also to queue 1. To separate video into queue 2, the engineer must modify the CoS-to-queue mapping using the 'mls qos srr-queue output cos-map' command, which reassigns CoS values to specific output queues. This directly overrides the default behavior and places video traffic in the correct queue.
A company is deploying a new campus network with a hierarchical design (core, distribution, access). The QoS design must ensure that voice traffic is prioritized end-to-end, and that marking is trusted only on access ports connected to IP phones. Which architectural approach should the architect take for classification and marking?
Explanation: It aligns with the Cisco QoS trust boundary model for campus networks. IP phones are trusted endpoints that mark voice traffic with the correct DSCP values (e.g., EF for voice, AF41 for video). By configuring the access switch port to trust DSCP from the IP phone, the marking is preserved end-to-end. Distribution and core switches then apply queuing policies (e.g., LLQ) based on these trusted markings, ensuring voice traffic receives priority treatment across the entire network.
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Practice all Qos questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Qos. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Qos questions on the 350-401 frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Qos is tested as part of the ENCOR 350-401 blueprint. Practicing with targeted Qos questions ensures you can handle any format or difficulty that appears.
Yes. Courseiva provides free 350-401 practice questions across all exam topics and domains. The platform includes topic-based practice, mock exams, missed-question review, bookmarked questions, and readiness tracking — no account required.
Difficulty is subjective, but Qos is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
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