350-401 Question #303: Real Exam Question with Answer & Explanation

Question

What are two considerations when using SSO as a network redundancy feature? (Choose two)

Options

• Aboth supervisors must be configured separately
• Bthe multicast state is preserved during switchover
• Cmust be combined with NSF to support uninterrupted Layer 2 operations
• Dmust be combined with NSF to support uninterrupted Layer 3 operations
• Erequires synchronization between supervisors in order to guarantee continuous connectivity

Explanation

SSO Network Redundancy Explanation

Stateful Switchover (SSO) synchronizes state information between active and standby supervisors, enabling seamless failover - but it has important limitations and requirements.

Why D and E are correct: SSO must be combined with Non-Stop Forwarding (NSF) to maintain uninterrupted Layer 3 operations (D), because SSO alone preserves control plane state but routing protocols still need NSF to continue forwarding packets without reconverging. SSO also fundamentally requires synchronization between supervisors (E) - without this real-time state mirroring, the standby supervisor wouldn't have the information needed to take over seamlessly.

Why the distractors are wrong: Option A is incorrect because both supervisors share the same configuration automatically - separate configuration defeats the purpose of SSO. Option B is incorrect because multicast state is not preserved during SSO switchover, which is a known limitation. Option C is wrong because SSO natively handles Layer 2 (switching) state preservation on its own; it's Layer 3 routing that requires NSF assistance.

Memory Tip: Think of SSO as a "synchronized handoff" - it needs a sync partner (supervisor synchronization) and a routing helper (NSF) to truly maintain full network continuity. "SSO syncs supervisors; NSF saves Layer 3."

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