Selected Answer: A The correct answer is A. enabling BFD for EIGRP on the access layer uplinks. Bidirectional Forwarding Detection (BFD) is a protocol used to detect failures in the forwarding path between two adjacent devices very quickly. By enabling BFD for EIGRP on the access layer uplinks, the engineer can greatly improve convergence time for access layer switch failures. BFD operates independently of the routing protocol and can detect failures faster than relying on routing protocol timers alone.

Selected Answer: A A is right because: B. Reducing EIGRP Hello / Hold timers This helps detection, but: Still slower than BFD Can raise CPU load and instability if pushed too far C. EIGRP summarization from core to aggregation layer Helps shrink the routing table and query scope Does not directly speed up failure detection at the access layer D. EIGRP summarization from access to aggregation layer Helps contain failures, but: Does not speed up detection Only limits how changes spread

Selected Answer: B I disagree, answer should be B : - Yes BFD can help reduce convergence time, but option A says to enable it only in the access layer, not in the aggregation layer too. BFS has to be enabled on both ends. - Cisco documentation "recommends in the Layer 3 campus design that the EIGRP hello and dead timers be reduced to 1 and 3 seconds, respectively" ... "Reducing the EIGRP hello and hold timers from defaults of 5 and 15 seconds provides for a faster routing convergence in the rare event that L1/2 remote fault detection fails" https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Campus/routed-ex.html#pgfId-1027653

Selected Answer: D It's D: When an access switch fails (power down or link down) on direct L3 copper uplinks, the physical link drops and the EIGRP neighborship on the aggregation switch tears down right away. Failure detection isn’t the bottleneck; the larger factor in EIGRP convergence is bounding the query domain when many connected routes behind the access switch disappear at once.