350-401 Question #374: Real Exam Question with Answer & Explanation

Question

In a three-tier hierarchical campus network design, which action is a design best-practice for the core layer?

Options

• Aprovide QoS prioritization services such as marking, queueing, and classification for critical network
• Bprovide redundant Layer 3 point-to-point links between the core devices for more predictable and
• Cprovide advanced network security features such as 802. IX, DHCP snooping, VACLs, and port
• Dprovide redundant aggregation for access layer devices and first-hop redundancy protocols such as

Explanation

Core Layer Design Best Practices

Option B is correct because the core layer's primary role is high-speed, reliable packet forwarding between distribution blocks. Redundant Layer 3 point-to-point links eliminate Spanning Tree Protocol (STP) complexity, provide deterministic failover, and ensure the fast, predictable switching that the core demands.

• Option A is wrong because QoS marking and classification belong at the distribution or access layer - by the time traffic reaches the core, it should already be marked and prioritized.
• Option C is wrong because advanced security features like 802.1X, DHCP snooping, and port security are access layer responsibilities, where end devices connect to the network.
• Option D is wrong because redundant aggregation and first-hop redundancy protocols (HSRP/VRRP) are distribution layer functions, which aggregate and provide gateway services for access layer devices.

🧠 Memory Tip: Think of the three layers as "Secure → Smart → Speed" - Access = Security, Distribution = Smart routing/policy, Core = Speed and redundancy. If a feature sounds like it controls or inspects traffic, it belongs below the core.

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