400-007 Exam Questions Tutorials

In this scenario, the application itself duplicates data transmission across two separate NICs on Host A, with the intention that at least one copy will reach Host B, regardless of any single path or link failure. While this increases redundancy at the application and host level, the underlying network must also support rapid failure recovery to avoid packet loss during convergence events.

Among the options provided:

A. EIGRP with feasible successors provides pre-computed backup routes but still requires routing protocol convergence upon failure, which could result in millisecond-scale interruption—enough to cause data loss if packets are in transit.

B. BFD (Bidirectional Forwarding Detection) offers rapid detection of link failures, but by itself does not provide traffic redirection or packet protection; it simply informs the routing protocol faster.

D. Static routes lack dynamic convergence capabilities and would not offer high availability across dynamic failure points unless manually configured with tracking—still less responsive and scalable.

C. IP Fast Reroute (IP FRR) is specifically designed to offer sub-50ms convergence time by pre-installing backup paths in the forwarding plane. Upon detecting a failure, traffic is immediately switched to the pre-computed alternate path without waiting for the routing protocol to reconverge. This ensures minimal disruption and best supports lossless delivery for high-availability applications.

IP FRR is consistent with CCDE v3.1 design principles where sub-second convergence and resiliency are critical in mission-critical enterprise and data center architectures.

C (Class-Based Weighted Fair Queuing - CBWFQ): CBWFQ allows assigning bandwidth limits (in this case, 2 Mbps) to specific traffic classes, effectively controlling scavenger traffic without dropping excess packets unnecessarily.

Other options explained:

A: Policing drops excess traffic immediately rather than queuing.

B: LLQ is for delay-sensitive traffic, not scavenger control.

D: Shaping is useful but typically applied at interface level, not specific traffic classes.

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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