Free Cisco 400-007 Practice Exam with Questions & Answers | Set: 11

A (MLAG/MC-LAG): Multi-chassis Link Aggregation (MLAG or MC-LAG) provides fast convergence by eliminating STP dependency and creating active-active Layer 2 uplinks.

E (UDLD): UniDirectional Link Detection helps quickly detect and disable one-way fiber failures, preventing loops before STP reacts.

Why other options are incorrect:

B: DHCP snooping provides security against rogue DHCP but not redundancy or fast convergence.

C: Root guard protects root bridge integrity but doesn’t enhance failover speed.

D: BPDU guard protects edge ports but does not contribute to core redundancy or convergence.

C (Complex and distributed management flow):SDN centralizes control-plane management, simplifying complex, distributed configuration and operational models, which is especially valuable in large-scale, dynamic cloud environments.

Other options explained:

A: SDN may assist, but intelligent monitoring is a separate operational task.

B: SDN does not directly address resource growth—it supports scalability but doesn’t limit application resource demands.

D: SDN may reduce OpEx, but the primary benefit is operational simplification rather than direct cost reduction.

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Increasing jitter buffer size smoothens jitter but at the cost of introducing additional delay.

Excessive jitter buffering can lead to perceptible audio or video lag, impacting user experience.

C: Therefore, the undesired effect is increased transport delay, potentially leading to quality issues if the buffer size is too large.

Why other options are incorrect:

A and D: Jitter buffering does not improve jitter itself; it masks it at the expense of delay.

B: Jitter compensation doesn ' t increase jitter, but delay.

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A (Access):QoS classification and marking should occur as close to the traffic source as possible—at the access layer—so that policies can be consistently applied throughout the network.

Other options explained:

B/D: QoS policies at these layers rely on markings applied earlier.

C: Collapsed core is simply core and distribution merged, but marking should still happen at access.

Comprehensive and Detailed Explanation:

To reduce oscillation and improve resiliency:

D: Increasing unequal-cost multipath (UCMP) paths allows the routing protocol to load-share over more than one path, preventing traffic congestion from oscillating between nodes.

E: Dual links to each site improve bandwidth and failover options, reducing reliance on overloaded peers.

Other options:

A: Increasing redundant paths may worsen convergence complexity and doesn ' t solve oscillation.

B: Removing inter-spoke links reduces redundancy.

C: Increasing convergence timers delays recovery and stability.

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A modular, scalable network design aims to:

Localize faults

Reduce impact radius of failures

Enable automated fault detection and recovery

The primary operational driver is to reduce the need for manual intervention during failures, which translates to:

Faster recovery times

Consistency in troubleshooting

Improved service reliability

While minimizing app downtime (B) is a goal, it is a result of reducing human-required failure recovery. Option C is a business process goal, and D is an architectural challenge, not an operational driver.

This aligns with CCDE v3.1 ' s “Network Architecture Principles” for building operationally resilient networks.