Cisco
400-007 · Question #6
400-007 Question #6: Real Exam Question with Answer & Explanation
The correct answer is A: Design MLAG/MC-LAG into the network wherever possible.. MC-LAG provides active-active Layer 2 redundancy with fast failover, and UDLD detects unidirectional link failures immediately - both directly address fast convergence and resiliency requirements.
Question
Company XYZ asks for design recommendations for Layer 2 redundancy. The company wants to prioritize fast convergence and resiliency elements in the design. Which two technologies are recommended? (Choose two.)
Options
- ADesign MLAG/MC-LAG into the network wherever possible.
- BConfigure DHCP snooping on the switches.
- CUse root guard.
- DUse BPDU guard.
- EUse UniDirectional Link Detection.
Explanation
MC-LAG provides active-active Layer 2 redundancy with fast failover, and UDLD detects unidirectional link failures immediately - both directly address fast convergence and resiliency requirements.
Common mistakes.
- B. DHCP snooping is a Layer 2 security feature that validates DHCP messages to block rogue DHCP servers; it has no effect on redundancy or convergence speed.
- C. Root guard enforces STP root bridge placement by blocking ports that receive superior BPDUs, which is a topology stability and security measure rather than a convergence acceleration or resiliency mechanism.
- D. BPDU guard disables access ports upon receipt of any BPDU to protect against unauthorized switch connections, serving a security purpose on edge ports rather than improving convergence or resiliency in the core.
Concept tested. MC-LAG and UDLD for Layer 2 redundancy and fast convergence
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