Cisco Updated 400-007 Exam Questions and Answers by euan

D (High latency):In three-tier architectures, east-west traffic between different pods (access domains) must traverse additional layers (distribution and core), introducing extra hops and thus adding latency. This inefficiency is one reason why spine-leaf architectures are favored for modern data centers.

Other options explained:

A: Bandwidth is less of a concern with high-speed core links.

B: Security is not directly affected by east-west traversal in this architecture.

C: Scalability is limited, but the primary issue for east-west traffic is latency.

D (Fate sharing):Fate sharing refers to a design where multiple dependent states fail together (i.e., when physical link fails, BGP session and its routes fail too).

Other options explained:

A: Fault isolation refers to containing failures, not dependent failure.

B: Resiliency is the ability to recover, not simultaneous failure.

C: Redundancy would prevent total loss if implemented.

B (Weighted Random Early Detection - WRED):WRED proactively drops packets before buffers are full to avoid global synchronization in TCP traffic and prevent tail drops, thus improving overall TCP performance under congestion.

Other options explained:

A: WFQ provides fairness but does not proactively avoid congestion.

C: LLQ is for delay-sensitive traffic, not congestion avoidance for TCP.

D: FIFO offers no QoS or congestion control.

A (Additional host routes):Spoke-to-spoke dynamic tunnels in DMVPN phase 3 result in OSPF populating routing tables with multiple /32 host routes for each spoke-to-spoke tunnel, which can impact scalability and routing table size.

Other options explained:

B: Priority changes not typically required.

C: Split-horizon issue is solved in DMVPN phase 3.

D: Spokes dynamically register with the hub; no manual spoke IP configuration needed.