A spine-leaf architecture offers significant advantages for modern data centers. First, it provides high scalability; capacity can be increased by adding more spine switches (for east-west bandwidth) or leaf switches (for server port density) without a major redesign. It also ensures predictable, low latency, as traffic between any two hosts is always just one hop across the spine. Second, the design is inherently redundant and fault-tolerant. With multiple spine switches, traffic is distributed via Equal-Cost Multi-Path (ECMP), and the failure of a single device or link has minimal impact on the fabric's overall performance.

B. A spine-leaf architecture is an internal data center topology; it does not inherently simplify or complicate integration with external WANs compared to other designs.

D. Spine-leaf architectures are typically built on Layer 3 to avoid the problems of large Layer 2 domains, effectively replacing complex L2 management (like STP) with L3 routing.

1. Juniper Networks TechLibrary. (2023). Benefits of an IP Fabric Architecture. "The key benefits of an IP fabric architecture are: ... Improved network scale... Improved resiliency... ECMP makes use of all available connections between the leaf and spine layers to load-balance traffic."

2. Juniper Networks. (2021). Day One: Data Center Fundamentals. Chapter 2

"Data Center Architectures

" Section "Spine and Leaf." "This architecture is highly scalable... The spine and leaf architecture is also very resilient."