Free Cisco 400-007 Practice Exam with Questions & Answers | Set: 6

D (Root Guard): Prevents unauthorized devices from becoming the STP root by blocking superior BPDUs on access ports.

E (BPDU Guard): Immediately shuts down ports that receive unexpected BPDUs, protecting against accidental or malicious connection of switches to access ports.

Why other options are incorrect:

A: Loop Guard protects against unidirectional link failures but not unauthorized devices.

B: PortFast speeds up STP convergence on access ports but does not provide security.

C: DTF (Dynamic Trunking Protocol) is not a security feature.

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Comprehensive and Detailed Explanation:

C: Moving workloads or backup/recovery functions to cloud platforms reduces capital expenditure by avoiding the cost of physical infrastructure, data centers, and maintenance. Cloud-based DRaaS (Disaster Recovery as a Service) offers scalability, resilience, and cost efficiency aligned with an OPEX model.

Other options:

A and B are security and software lifecycle tasks, not cost-effective DR strategies.

D increases CAPEX by building and maintaining additional infrastructure.

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For EIGRP to maintain loop-free alternate paths, the feasibility condition must be met:

A. The Reported Distance (RD) must be lower than the router ' s Feasible Distance (FD).

E. A feasible successor must exist (i.e., an alternate next-hop satisfying the feasibility condition).

This design allows immediate failover without recomputation, ensuring fast convergence — a critical CCDE v3.1 protocol design principle.

Why other options are incorrect:

B, C, D: Misstate the feasibility condition or confuse RD and FD relationships.

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D: CWDM (Coarse Wavelength Division Multiplexing) shares parts of the same optical transmission window (1260–1625 nm) as DWDM but uses wider spacing between channels (typically 20 nm apart).

E: CWDM typically uses passive devices (multiplexers and demultiplexers) that require no electrical power, making deployment cost-effective.

Incorrect Options:

A: CWDM is better suited for shorter distances (up to ~80 km) and doesn ' t typically use optical amplifiers (EDFA). DWDM is better for long-haul with amplification.

B: 850 nm is used in multimode fiber systems (not CWDM).

C: CWDM supports up to 18 channels; DWDM supports up to 32 or more.

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In OSPF, a ring topology typically converges more slowly because:

Link failures can create longer SPF recalculations as alternate paths are fewer.

Only one alternate path usually exists for each link failure, extending the time needed for failure detection and SPF recalculation.

CCDE v3.1 stresses that designs like full mesh or triangulated topologies provide faster convergence due to multiple available alternate paths, which reduce SPF computation complexity.

Why other options are incorrect:

A, D, E: These topologies provide multiple paths.

B: Full mesh offers immediate redundancy for any failure.

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B (Strong cryptography for cardholder data):PCI DSS requires strong cryptographic protocols (e.g. TLS 1.2 or higher) to protect sensitive data during processing and storage.

C (Strong encryption for transmission):Data-in-transit across public or untrusted networks must be encrypted using strong protocols to comply with PCI DSS.

Other options explained:

A/D/E: These are general security best practices but not directly tied to TLS upgrade compliance for cardholder data under PCI DSS.