Which Configuration Provides Port Redundancy Between Switches?
Short answer
D Link aggregation
Question
Key Takeaways
Tests understanding of Ethernet link bonding protocols versus basic VLAN or duplex settings, with the trap being confusion between trunking/tagging and actual link-level redundancy.
Link aggregation (EtherChannel/LACP) combines multiple physical switch ports into a single logical link to provide both increased bandwidth and automatic failover redundancy. Community consensus confirms it as the standard solution for switch-to-switch port redundancy in CompTIA Network+.
Common mistake: None recorded due to unanimous voting, but candidates often incorrectly select 802.1Q tagging, mistakenly assuming VLAN trunking inherently prevents physical link failures rather than merely segmenting broadcast domains.
Expert Analysis
Why the Answer Is Correct
Link aggregation (IEEE 802.3ad/LACP) bonds multiple physical interfaces into one logical channel. This setup automatically distributes traffic and provides hardware-level redundancy; if one cable or port fails, the remaining link maintains connectivity without dropping sessions. CompTIA frequently tests this as the primary method for switch-to-switch fault tolerance.
Why the Other Options Are Wrong
Full duplex simply allows simultaneous bidirectional transmission on a single link and offers no multi-port failover. 802.1Q tagging and Native VLAN are Layer 2 VLAN encapsulation methods used on trunk links to segment traffic, not to create redundant physical paths. While trunks can run over aggregated links, tagging itself does not prevent link failure from causing outages.
Community Comment Notes
Users consistently validate D, noting that link aggregation explicitly combines NICs or switch ports in tandem to boost throughput and resilience [1][2]. One comment clarifies it connects multiple interfaces to increase bandwidth while maintaining fault tolerance, aligning with real-world deployment practices [3]. No significant debate exists, confirming straightforward alignment with official exam objectives.
Official Reference
These links open the official vendor documentation in a new tab.
Exam Strategy
When troubleshooting or designing switch interconnects, always look for keywords like multiple ports, bandwidth, and failover to trigger link aggregation. Memorize that LACP operates at Layer 1/2 and handles both load balancing and redundancy, distinctly different from Spanning Tree Protocol which blocks redundant paths rather than combining them.
Community Votes
100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 3
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chupapi_001 👍 5 Answered DThe correct answer is D: Link aggregation.
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favouralain 👍 2 Answered DLink aggregation is the combining of multiple network connections in parallel by any of several methods.
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HeatSquad77 👍 1 Answered DD. link aggregation Connecting multiple NICs in tandem to increase bandwidth in smaller increments
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