Cisco CCNP 350-401 ENCOR Enterprise Architecture, High Availability, and QoS Design Practice Test 1

 

Topic 01 Practice Test 1 covers Enterprise Architecture, High Availability, and QoS Design for Cisco 350-401 ENCOR. For broader exam preparation, review the Cisco 350-401 ENCOR Exam Dumps. Every option includes focused technical reasoning explaining both the Cisco enterprise networking concept and its fit to the scenario.

Question 1

During an availability review, the requirement is to scale a multi-building campus without stretching access-layer failure domains into the core. Which approach should be selected? Choose ONE.

1. equal-cost multipath (ECMP)
2. MQC class-map
3. three-tier campus architecture
4. class-based weighted fair queuing (CBWFQ)

Correct Answer(s)

 

C

Rationale

1. equal-cost multipath (ECMP) is intended for cases that must use two equal-metric routed uplinks concurrently instead of leaving one idle. the routing table can keep multiple equal-cost next hops active at the same time. In this question three-tier campus architecture matches the requirement, whereas equal-cost multipath (ECMP) addresses a different need.
2. MQC class-map serves environments that must separate the description of traffic membership from the actions taken on that class. named match criteria provide a reusable boundary between classification and QoS action. The scenario requires three-tier campus architecture, not MQC class-map, because the operational constraints differ.
3. Choose three-tier campus architecture because distinct distribution blocks contain local failures while the core remains a fast transport layer. Here the controlling requirement is to scale a multi-building campus without stretching access-layer failure domains into the core, so this feature aligns with the actual decision in the stem.
4. class-based weighted fair queuing (CBWFQ) helps when engineers need to protect several non-real-time application classes from starvation on a congested link. CBWFQ is suited to differentiated data classes that need bandwidth assurance rather than minimal latency. The stem instead depends on three-tier campus architecture; class-based weighted fair queuing (CBWFQ) therefore does not resolve the tested requirement.

 

Question 2

During a configuration standards review, a proposed change must minimize campus tiers because only a few access blocks exist and a dedicated core adds no scaling benefit. Which technology or configuration is the best match? Choose ONE.

1. ingress marking
2. QoS trust boundary
3. collapsed-core two-tier architecture
4. traffic shaping

Correct Answer(s)

 

C

Rationale

1. ingress marking applies when the goal is to set trusted DSCP values before traffic enters a bandwidth-constrained routed core. early marking gives subsequent hops a consistent signal for queuing and congestion treatment. This case calls for collapsed-core two-tier architecture; choosing ingress marking would address another technical problem.
2. QoS trust boundary serves environments that must prevent user endpoints from self-marking bulk traffic as voice while trusting markings from managed phones. the trust decision belongs at the controlled edge where endpoint identity and device type are known. The scenario requires collapsed-core two-tier architecture, not QoS trust boundary, because the operational constraints differ.
3. Use collapsed-core two-tier architecture here because combining core and distribution avoids an unnecessary tier at this site size. The stated constraint is to minimize campus tiers because only a few access blocks exist and a dedicated core adds no scaling benefit, making this option the closest functional match for the scenario.
4. traffic shaping supports designs that need to enforce an average transmit rate while tolerating short bursts through local buffering. buffering makes shaping appropriate when the sender should adapt to a slower downstream service. Unlike collapsed-core two-tier architecture, traffic shaping misses the requirement that controls this scenario.

 

Question 3

During an application modernization effort, operations has one primary objective: support heavy east-west server traffic with consistent hop count across racks. Which option aligns most closely with that objective? Choose ONE.

1. spine-leaf fabric
2. hierarchical QoS
3. traffic policing
4. DSCP EF marking

Correct Answer(s)

 

A

Rationale

1. The best fit is spine-leaf fabric because every leaf reaches every spine, enabling ECMP and a consistent leaf-to-leaf path length. The environment must support heavy east-west server traffic with consistent hop count across racks; that is the exact operational property the scenario is testing.
2. hierarchical QoS is intended for cases that must apply class-level queuing beneath an overall tunnel or subinterface bandwidth cap. a single flat policy cannot independently express both aggregate pacing and subordinate class scheduling as cleanly. In this question spine-leaf fabric matches the requirement, whereas hierarchical QoS addresses a different need.
3. traffic policing fits situations where teams need to apply a non-buffering rate limit at a trust boundary and mark violators down. the requirement favors immediate enforcement rather than delayed transmission. Here spine-leaf fabric provides the required behavior, while traffic policing serves a separate purpose.
4. DSCP EF marking applies when the goal is to preserve a consistent network-layer marking for latency-sensitive RTP traffic across routed hops. a Layer 3 DSCP value survives routed boundaries more naturally than an 802.1p-only tag. This case calls for spine-leaf fabric; choosing DSCP EF marking would address another technical problem.

 

Question 4

During a brownfield integration, the team is comparing several technically valid features, but it specifically needs to avoid spanning-tree dependence across access-to-distribution uplinks and use equal-cost routed paths. Which choice is most appropriate? Choose ONE.

1. routed access design
2. StackWise Virtual pair
3. Weighted Random Early Detection (WRED)
4. low-latency queue (LLQ)

Correct Answer(s)

 

A

Rationale

1. routed access design fits because layer 3 access uplinks remove the campus uplinks from the spanning-tree topology. In this scenario, the team must avoid spanning-tree dependence across access-to-distribution uplinks and use equal-cost routed paths; that requirement directly matches the role of routed access design.
2. StackWise Virtual pair serves environments that must reduce first-hop and spanning-tree complexity by making a redundant distribution pair act as one logical switch. logical switch virtualization lets a downstream channel span the two physical chassis. The scenario requires routed access design, not StackWise Virtual pair, because the operational constraints differ.
3. Weighted Random Early Detection (WRED) helps when engineers need to signal congestion to TCP flows before an egress queue reaches complete exhaustion. early probabilistic drops encourage TCP senders to reduce rate before the queue is completely full. The stem instead depends on routed access design; Weighted Random Early Detection (WRED) therefore does not resolve the tested requirement.
4. low-latency queue (LLQ) is intended for cases that must reduce latency and jitter for interactive media when an egress interface is oversubscribed. the mechanism serves real-time traffic before weighted classes while controlling priority bandwidth. In this question routed access design matches the requirement, whereas low-latency queue (LLQ) addresses a different need.

 

Question 5

During an audit of failure domains, a production constraint requires the environment to survive an active supervisor failure without rebuilding all control state from scratch. Which option solves that requirement without addressing a different problem? Choose ONE.

1. MQC class-map
2. stateful supervisor switchover (SSO)
3. class-based weighted fair queuing (CBWFQ)
4. out-of-band management network

Correct Answer(s)

 

B

Rationale

1. MQC class-map applies when the goal is to separate the description of traffic membership from the actions taken on that class. named match criteria provide a reusable boundary between classification and QoS action. This case calls for stateful supervisor switchover (SSO); choosing MQC class-map would address another technical problem.
2. The best fit is stateful supervisor switchover (SSO) because the standby supervisor maintains synchronized state and can take over rapidly. The environment must survive an active supervisor failure without rebuilding all control state from scratch; that is the exact operational property the scenario is testing.
3. class-based weighted fair queuing (CBWFQ) supports designs that need to protect several non-real-time application classes from starvation on a congested link. CBWFQ is suited to differentiated data classes that need bandwidth assurance rather than minimal latency. Unlike stateful supervisor switchover (SSO), class-based weighted fair queuing (CBWFQ) misses the requirement that controls this scenario.
4. out-of-band management network fits situations where teams need to preserve administrative reachability during a routing failure in the production network. a physically or logically separate management path remains usable when production routing fails. Here stateful supervisor switchover (SSO) provides the required behavior, while out-of-band management network serves a separate purpose.

 

Question 6

During a compliance-driven change, the engineering team needs to keep data forwarding active while the routing control plane reconverges after a switchover. Which option most directly satisfies this requirement? Choose ONE.

1. traffic shaping
2. N+1 infrastructure redundancy
3. Nonstop Forwarding (NSF)
4. ingress marking

Correct Answer(s)

 

C

Rationale

1. traffic shaping fits situations where teams need to smooth bursty output so a downstream policer is less likely to drop packets. the egress scheduler can pace traffic to the contracted rate and absorb temporary bursts. Here Nonstop Forwarding (NSF) provides the required behavior, while traffic shaping serves a separate purpose.
2. N+1 infrastructure redundancy helps when engineers need to maintain required service capacity after a single shared infrastructure component fails. the model is appropriate when pooled resources can share a common standby spare. The stem instead depends on Nonstop Forwarding (NSF); N+1 infrastructure redundancy therefore does not resolve the tested requirement.
3. Nonstop Forwarding (NSF) fits because the forwarding plane continues using existing entries while control-plane state is rebuilt. In this scenario, the team must keep data forwarding active while the routing control plane reconverges after a switchover; that requirement directly matches the role of Nonstop Forwarding (NSF).
4. ingress marking is intended for cases that must set trusted DSCP values before traffic enters a bandwidth-constrained routed core. early marking gives subsequent hops a consistent signal for queuing and congestion treatment. In this question Nonstop Forwarding (NSF) matches the requirement, whereas ingress marking addresses a different need.

 

Question 7

During a multi-site design review, engineers must use two equal-metric routed uplinks concurrently instead of leaving one idle. Which choice best addresses the decisive constraint? Choose ONE.

1. three-tier campus architecture
2. traffic policing
3. hierarchical QoS
4. equal-cost multipath (ECMP)

Correct Answer(s)

 

D

Rationale

1. three-tier campus architecture supports designs that need to add buildings while preserving modular fault isolation and predictable convergence. modular building blocks reduce the blast radius of changes and simplify horizontal campus growth. Unlike equal-cost multipath (ECMP), three-tier campus architecture misses the requirement that controls this scenario.
2. traffic policing helps when engineers need to apply a non-buffering rate limit at a trust boundary and mark violators down. the requirement favors immediate enforcement rather than delayed transmission. The stem instead depends on equal-cost multipath (ECMP); traffic policing therefore does not resolve the tested requirement.
3. hierarchical QoS serves environments that must shape an interface to a carrier rate and still prioritize voice within that shaped bandwidth. the parent can shape the aggregate while the child decides how classes use the shaped bandwidth. The scenario requires equal-cost multipath (ECMP), not hierarchical QoS, because the operational constraints differ.
4. Choose equal-cost multipath (ECMP) because the routing table can keep multiple equal-cost next hops active at the same time. Here the controlling requirement is to use two equal-metric routed uplinks concurrently instead of leaving one idle, so this feature aligns with the actual decision in the stem.

 

Question 8

During acceptance testing, the current design does not prevent user endpoints from self-marking bulk traffic as voice while trusting markings from managed phones. What should the team implement to correct the design with the most direct fit? Choose ONE.

1. QoS trust boundary
2. collapsed-core two-tier architecture
3. Weighted Random Early Detection (WRED)
4. StackWise Virtual pair

Correct Answer(s)

 

A

Rationale

1. Use QoS trust boundary here because the trust decision belongs at the controlled edge where endpoint identity and device type are known. The stated constraint is to prevent user endpoints from self-marking bulk traffic as voice while trusting markings from managed phones, making this option the closest functional match for the scenario.
2. collapsed-core two-tier architecture fits situations where teams need to reduce operational complexity where distribution switches can also provide the campus backbone. the smaller topology gains fewer failure points without sacrificing dual-homed access. Here QoS trust boundary provides the required behavior, while collapsed-core two-tier architecture serves a separate purpose.
3. Weighted Random Early Detection (WRED) supports designs that need to signal congestion to TCP flows before an egress queue reaches complete exhaustion. early probabilistic drops encourage TCP senders to reduce rate before the queue is completely full. Unlike QoS trust boundary, Weighted Random Early Detection (WRED) misses the requirement that controls this scenario.
4. StackWise Virtual pair applies when the goal is to reduce first-hop and spanning-tree complexity by making a redundant distribution pair act as one logical switch. logical switch virtualization lets a downstream channel span the two physical chassis. This case calls for QoS trust boundary; choosing StackWise Virtual pair would address another technical problem.

 

Question 9

During an infrastructure-as-code review, the requirement is to identify real-time voice packets so downstream QoS policies can place them in the expedited class. Which approach should be selected? Choose ONE.

1. out-of-band management network
2. DSCP EF marking
3. spine-leaf fabric
4. MQC class-map

Correct Answer(s)

 

B

Rationale

1. out-of-band management network helps when engineers need to preserve administrative reachability during a routing failure in the production network. a physically or logically separate management path remains usable when production routing fails. The stem instead depends on DSCP EF marking; out-of-band management network therefore does not resolve the tested requirement.
2. Choose DSCP EF marking because eF is the conventional DiffServ behavior used for low-loss, low-latency voice treatment. Here the controlling requirement is to identify real-time voice packets so downstream QoS policies can place them in the expedited class, so this feature aligns with the actual decision in the stem.
3. spine-leaf fabric serves environments that must expand data-center capacity by adding leaf switches without redesigning a hierarchical aggregation layer. horizontal leaf growth preserves the fabric pattern and avoids a chokepoint aggregation tier. The scenario requires DSCP EF marking, not spine-leaf fabric, because the operational constraints differ.
4. MQC class-map is intended for cases that must separate the description of traffic membership from the actions taken on that class. named match criteria provide a reusable boundary between classification and QoS action. In this question DSCP EF marking matches the requirement, whereas MQC class-map addresses a different need.

 

Question 10

During an operations handoff, a proposed change must protect a small voice class from queueing delay on a congested WAN edge. Which technology or configuration is the best match? Choose ONE.

1. N+1 infrastructure redundancy
2. routed access design
3. ingress marking
4. low-latency queue (LLQ)

Correct Answer(s)

 

D

Rationale

1. N+1 infrastructure redundancy supports designs that need to maintain required service capacity after a single shared infrastructure component fails. the model is appropriate when pooled resources can share a common standby spare. Unlike low-latency queue (LLQ), N+1 infrastructure redundancy misses the requirement that controls this scenario.
2. routed access design applies when the goal is to use both redundant uplinks actively instead of blocking one as a Layer 2 loop-prevention path. ECMP-capable routed uplinks can forward simultaneously without creating a Layer 2 loop. This case calls for low-latency queue (LLQ); choosing routed access design would address another technical problem.
3. ingress marking serves environments that must apply policy as close as practical to the source so later queues can act on a stable marking. the edge has better endpoint context and can establish a trustworthy packet marking. The scenario requires low-latency queue (LLQ), not ingress marking, because the operational constraints differ.
4. Use low-latency queue (LLQ) here because strict priority service addresses delay and jitter when the link is congested. The stated constraint is to protect a small voice class from queueing delay on a congested WAN edge, making this option the closest functional match for the scenario.

 

Question 11

During final design validation, operations has one primary objective: guarantee a minimum share to business-critical data while allowing unused bandwidth to be shared. Which option aligns most closely with that objective? Choose ONE.

1. three-tier campus architecture
2. class-based weighted fair queuing (CBWFQ)
3. stateful supervisor switchover (SSO)
4. hierarchical QoS

Correct Answer(s)

 

B

Rationale

1. three-tier campus architecture fits situations where teams need to keep distribution policy aggregation separate from a high-speed campus backbone. the design preserves separate access, policy aggregation, and backbone responsibilities. Here class-based weighted fair queuing (CBWFQ) provides the required behavior, while three-tier campus architecture serves a separate purpose.
2. The best fit is class-based weighted fair queuing (CBWFQ) because configured class bandwidth is enforced when congestion occurs and unused capacity can be shared. The environment must guarantee a minimum share to business-critical data while allowing unused bandwidth to be shared; that is the exact operational property the scenario is testing.
3. stateful supervisor switchover (SSO) is intended for cases that must survive an active supervisor failure without rebuilding all control state from scratch. the standby supervisor maintains synchronized state and can take over rapidly. In this question class-based weighted fair queuing (CBWFQ) matches the requirement, whereas stateful supervisor switchover (SSO) addresses a different need.
4. hierarchical QoS applies when the goal is to shape an interface to a carrier rate and still prioritize voice within that shaped bandwidth. the parent can shape the aggregate while the child decides how classes use the shaped bandwidth. This case calls for class-based weighted fair queuing (CBWFQ); choosing hierarchical QoS would address another technical problem.

 

Question 12

During a resilience test, the team is comparing several technically valid features, but it specifically needs to limit a fast LAN-to-WAN egress to a provider rate without discarding every temporary burst. Which choice is most appropriate? Choose ONE.

1. StackWise Virtual pair
2. Nonstop Forwarding (NSF)
3. traffic shaping
4. collapsed-core two-tier architecture

Correct Answer(s)

 

C

Rationale

1. StackWise Virtual pair is intended for cases that must reduce first-hop and spanning-tree complexity by making a redundant distribution pair act as one logical switch. logical switch virtualization lets a downstream channel span the two physical chassis. In this question traffic shaping matches the requirement, whereas StackWise Virtual pair addresses a different need.
2. Nonstop Forwarding (NSF) serves environments that must keep data forwarding active while the routing control plane reconverges after a switchover. the forwarding plane continues using existing entries while control-plane state is rebuilt. The scenario requires traffic shaping, not Nonstop Forwarding (NSF), because the operational constraints differ.
3. traffic shaping fits because shaping delays excess packets in a queue instead of immediately dropping them. In this scenario, the team must limit a fast LAN-to-WAN egress to a provider rate without discarding every temporary burst; that requirement directly matches the role of traffic shaping.
4. collapsed-core two-tier architecture helps when engineers need to reduce operational complexity where distribution switches can also provide the campus backbone. the smaller topology gains fewer failure points without sacrificing dual-homed access. The stem instead depends on traffic shaping; collapsed-core two-tier architecture therefore does not resolve the tested requirement.

 

Question 13

During a maintenance window, a production constraint requires the environment to enforce a hard ingress rate where excess packets must be discarded or remarked. Which option solves that requirement without addressing a different problem? Choose ONE.

1. traffic policing
2. equal-cost multipath (ECMP)
3. spine-leaf fabric
4. out-of-band management network

Correct Answer(s)

 

A

Rationale

1. The best fit is traffic policing because policing acts on out-of-profile packets immediately and does not smooth them in a delay queue. The environment must enforce a hard ingress rate where excess packets must be discarded or remarked; that is the exact operational property the scenario is testing.
2. equal-cost multipath (ECMP) fits situations where teams need to retain forwarding capacity after one of several equal-cost links fails. loss of one ECMP member leaves other installed next hops available. Here traffic policing provides the required behavior, while equal-cost multipath (ECMP) serves a separate purpose.
3. spine-leaf fabric applies when the goal is to expand data-center capacity by adding leaf switches without redesigning a hierarchical aggregation layer. horizontal leaf growth preserves the fabric pattern and avoids a chokepoint aggregation tier. This case calls for traffic policing; choosing spine-leaf fabric would address another technical problem.
4. out-of-band management network supports designs that need to preserve administrative reachability during a routing failure in the production network. a physically or logically separate management path remains usable when production routing fails. Unlike traffic policing, out-of-band management network misses the requirement that controls this scenario.

 

Question 14

During a design workshop, the engineering team needs to signal congestion to TCP flows before an egress queue reaches complete exhaustion. Which option most directly satisfies this requirement? Choose ONE.

1. routed access design
2. Weighted Random Early Detection (WRED)
3. QoS trust boundary
4. N+1 infrastructure redundancy

Correct Answer(s)

 

B

Rationale

1. routed access design is intended for cases that must use both redundant uplinks actively instead of blocking one as a Layer 2 loop-prevention path. ECMP-capable routed uplinks can forward simultaneously without creating a Layer 2 loop. In this question Weighted Random Early Detection (WRED) matches the requirement, whereas routed access design addresses a different need.
2. Weighted Random Early Detection (WRED) fits because early probabilistic drops encourage TCP senders to reduce rate before the queue is completely full. In this scenario, the team must signal congestion to TCP flows before an egress queue reaches complete exhaustion; that requirement directly matches the role of Weighted Random Early Detection (WRED).
3. QoS trust boundary helps when engineers need to prevent user endpoints from self-marking bulk traffic as voice while trusting markings from managed phones. the trust decision belongs at the controlled edge where endpoint identity and device type are known. The stem instead depends on Weighted Random Early Detection (WRED); QoS trust boundary therefore does not resolve the tested requirement.
4. N+1 infrastructure redundancy fits situations where teams need to tolerate one component failure while avoiding the expense of a fully duplicated 2N design. one additional unit covers a single failure without doubling every component. Here Weighted Random Early Detection (WRED) provides the required behavior, while N+1 infrastructure redundancy serves a separate purpose.

 

Question 15

During a security review, engineers must match voice signaling by ACL or protocol attributes before assigning a QoS action. Which choice best addresses the decisive constraint? Choose ONE.

1. DSCP EF marking
2. MQC class-map
3. three-tier campus architecture
4. stateful supervisor switchover (SSO)

Correct Answer(s)

 

B

Rationale

802. DSCP EF marking supports designs that need to preserve a consistent network-layer marking for latency-sensitive RTP traffic across routed hops. a Layer 3 DSCP value survives routed boundaries more naturally than an 802.1p-only tag. Unlike MQC class-map, DSCP EF marking misses the requirement that controls this scenario.
803. Choose MQC class-map because a class-map identifies which packets belong to a class; it does not itself schedule or police them. Here the controlling requirement is to match voice signaling by ACL or protocol attributes before assigning a QoS action, so this feature aligns with the actual decision in the stem.
804. three-tier campus architecture helps when engineers need to keep distribution policy aggregation separate from a high-speed campus backbone. the design preserves separate access, policy aggregation, and backbone responsibilities. The stem instead depends on MQC class-map; three-tier campus architecture therefore does not resolve the tested requirement.
805. stateful supervisor switchover (SSO) serves environments that must increase chassis control-plane availability by maintaining an immediately usable standby supervisor. a hot standby supervisor reduces the disruption caused by a control-plane hardware failure. The scenario requires MQC class-map, not stateful supervisor switchover (SSO), because the operational constraints differ.

 

Question 16

During a capacity review, the current design does not set trusted DSCP values before traffic enters a bandwidth-constrained routed core. What should the team implement to correct the design with the most direct fit? Choose ONE.

1. Nonstop Forwarding (NSF)
2. collapsed-core two-tier architecture
3. low-latency queue (LLQ)
4. ingress marking

Correct Answer(s)

 

D

Rationale

1. Nonstop Forwarding (NSF) applies when the goal is to keep data forwarding active while the routing control plane reconverges after a switchover. the forwarding plane continues using existing entries while control-plane state is rebuilt. This case calls for ingress marking; choosing Nonstop Forwarding (NSF) would address another technical problem.
2. collapsed-core two-tier architecture supports designs that need to reduce operational complexity where distribution switches can also provide the campus backbone. the smaller topology gains fewer failure points without sacrificing dual-homed access. Unlike ingress marking, collapsed-core two-tier architecture misses the requirement that controls this scenario.
3. low-latency queue (LLQ) fits situations where teams need to give real-time packets priority service while still policing the priority class to prevent starvation. LLQ combines class-based queuing with a bounded priority class. Here ingress marking provides the required behavior, while low-latency queue (LLQ) serves a separate purpose.
4. Use ingress marking here because early marking gives subsequent hops a consistent signal for queuing and congestion treatment. The stated constraint is to set trusted DSCP values before traffic enters a bandwidth-constrained routed core, making this option the closest functional match for the scenario.

 

Question 17

During preproduction validation, the requirement is to shape an interface to a carrier rate and still prioritize voice within that shaped bandwidth. Which approach should be selected? Choose ONE.

1. class-based weighted fair queuing (CBWFQ)
2. equal-cost multipath (ECMP)
3. hierarchical QoS
4. spine-leaf fabric

Correct Answer(s)

 

C

Rationale

1. class-based weighted fair queuing (CBWFQ) serves environments that must guarantee a minimum share to business-critical data while allowing unused bandwidth to be shared. configured class bandwidth is enforced when congestion occurs and unused capacity can be shared. The scenario requires hierarchical QoS, not class-based weighted fair queuing (CBWFQ), because the operational constraints differ.
2. equal-cost multipath (ECMP) helps when engineers need to retain forwarding capacity after one of several equal-cost links fails. loss of one ECMP member leaves other installed next hops available. The stem instead depends on hierarchical QoS; equal-cost multipath (ECMP) therefore does not resolve the tested requirement.
3. Choose hierarchical QoS because the parent can shape the aggregate while the child decides how classes use the shaped bandwidth. Here the controlling requirement is to shape an interface to a carrier rate and still prioritize voice within that shaped bandwidth, so this feature aligns with the actual decision in the stem.
4. spine-leaf fabric is intended for cases that must expand data-center capacity by adding leaf switches without redesigning a hierarchical aggregation layer. horizontal leaf growth preserves the fabric pattern and avoids a chokepoint aggregation tier. In this question hierarchical QoS matches the requirement, whereas spine-leaf fabric addresses a different need.

 

Question 18

During a root-cause investigation, a proposed change must dual-home an access switch to two distribution chassis while presenting one logical port-channel peer. Which technology or configuration is the best match? Choose ONE.

1. routed access design
2. QoS trust boundary
3. traffic shaping
4. StackWise Virtual pair

Correct Answer(s)

 

D

Rationale

1. routed access design serves environments that must contain Layer 2 failures within an access switch while allowing fast routed convergence upstream. routing contains broadcast and STP failure domains at the access block. The scenario requires StackWise Virtual pair, not routed access design, because the operational constraints differ.
2. QoS trust boundary supports designs that need to prevent user endpoints from self-marking bulk traffic as voice while trusting markings from managed phones. the trust decision belongs at the controlled edge where endpoint identity and device type are known. Unlike StackWise Virtual pair, QoS trust boundary misses the requirement that controls this scenario.
3. traffic shaping applies when the goal is to smooth bursty output so a downstream policer is less likely to drop packets. the egress scheduler can pace traffic to the contracted rate and absorb temporary bursts. This case calls for StackWise Virtual pair; choosing traffic shaping would address another technical problem.
4. Use StackWise Virtual pair here because the paired switches present a unified control and forwarding construct for supported multichassis links. The stated constraint is to dual-home an access switch to two distribution chassis while presenting one logical port-channel peer, making this option the closest functional match for the scenario.

 

Question 19

During a scalability assessment, operations has one primary objective: preserve administrative reachability during a routing failure in the production network. Which option aligns most closely with that objective? Choose ONE.

1. out-of-band management network
2. traffic policing
3. stateful supervisor switchover (SSO)
4. DSCP EF marking

Correct Answer(s)

 

A

Rationale

1. The best fit is out-of-band management network because a physically or logically separate management path remains usable when production routing fails. The environment must preserve administrative reachability during a routing failure in the production network; that is the exact operational property the scenario is testing.
2. traffic policing is intended for cases that must apply a non-buffering rate limit at a trust boundary and mark violators down. the requirement favors immediate enforcement rather than delayed transmission. In this question out-of-band management network matches the requirement, whereas traffic policing addresses a different need.
3. stateful supervisor switchover (SSO) applies when the goal is to increase chassis control-plane availability by maintaining an immediately usable standby supervisor. a hot standby supervisor reduces the disruption caused by a control-plane hardware failure. This case calls for out-of-band management network; choosing stateful supervisor switchover (SSO) would address another technical problem.
4. DSCP EF marking fits situations where teams need to identify real-time voice packets so downstream QoS policies can place them in the expedited class. EF is the conventional DiffServ behavior used for low-loss, low-latency voice treatment. Here out-of-band management network provides the required behavior, while DSCP EF marking serves a separate purpose.

 

Question 20

During a recovery rehearsal, the team is comparing several technically valid features, but it specifically needs to tolerate one component failure while avoiding the expense of a fully duplicated 2N design. Which choice is most appropriate? Choose ONE.

1. low-latency queue (LLQ)
2. Weighted Random Early Detection (WRED)
3. Nonstop Forwarding (NSF)
4. N+1 infrastructure redundancy

Correct Answer(s)

 

D

Rationale

1. low-latency queue (LLQ) helps when engineers need to give real-time packets priority service while still policing the priority class to prevent starvation. LLQ combines class-based queuing with a bounded priority class. The stem instead depends on N+1 infrastructure redundancy; low-latency queue (LLQ) therefore does not resolve the tested requirement.
2. Weighted Random Early Detection (WRED) serves environments that must reduce global TCP synchronization caused by many flows experiencing tail drop at once. WRED is congestion avoidance, unlike queuing mechanisms that only choose service order. The scenario requires N+1 infrastructure redundancy, not Weighted Random Early Detection (WRED), because the operational constraints differ.
3. Nonstop Forwarding (NSF) is intended for cases that must keep data forwarding active while the routing control plane reconverges after a switchover. the forwarding plane continues using existing entries while control-plane state is rebuilt. In this question N+1 infrastructure redundancy matches the requirement, whereas Nonstop Forwarding (NSF) addresses a different need.
4. N+1 infrastructure redundancy fits because one additional unit covers a single failure without doubling every component. In this scenario, the team must tolerate one component failure while avoiding the expense of a fully duplicated 2N design; that requirement directly matches the role of N+1 infrastructure redundancy.

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