350-401 · Question #100
350-401 Question #100: Real Exam Question with Answer & Explanation
The correct answer is D: Each hash maps directly to a single entry in the adjacency table. CEF Load Balancing Explanation CEF performs per-destination load balancing by combining the source and destination IP addresses to create a hash value (making E correct), and each resulting hash maps directly to a single entry in the adjacency table - not the RIB - which contains
Question
Which two statements about Cisco Express Forwarding load balancing are true?
Options
- ACisco Express Forwarding can load-balance over a maximum of two destinations
- BIt combines the source IP address subnet mask to create a hash for each destination
- CEach hash maps directly to a single entry in the RIB
- DEach hash maps directly to a single entry in the adjacency table
- EIt combines the source and destination IP addresses to create a hash for each destination
Explanation
CEF Load Balancing Explanation
CEF performs per-destination load balancing by combining the source and destination IP addresses to create a hash value (making E correct), and each resulting hash maps directly to a single entry in the adjacency table - not the RIB - which contains Layer 2 next-hop information needed for actual packet forwarding (making D correct).
Why the distractors are wrong:
- A is incorrect because CEF can load-balance over up to 16 destinations (not just two)
- B is incorrect because CEF uses the source and destination IP addresses, not subnet masks, to generate the hash
- C is incorrect because the hash maps to the adjacency table, not the RIB (Routing Information Base); the FIB references the adjacency table for forwarding decisions
💡 Memory Tip
Think "S+D = Hash → Adj": CEF takes Source + Destination addresses → creates a Hash → points to the Adjacency table. This reminds you of both correct answers simultaneously - the input (E) and the output (D) of the hashing process.
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