Difficulty: Easy
Correct Answer: physical layer
Explanation:
Introduction / Context:
The OSI model splits networking into seven layers. The lowest layer defines the mechanical, electrical, optical, and procedural characteristics for moving bits across a link. Identifying this layer is foundational for troubleshooting cabling, signaling, and connectors.
Given Data / Assumptions:
Concept / Approach:
Layer 1 is the Physical layer. It specifies voltage levels, timing, pinouts, modulation, line coding, wavelengths, and connectors. It does not include framing or addressing (Layer 2) nor routing (Layer 3).
Step-by-Step Solution:
Recall OSI stack from bottom up: Physical, Data Link, Network, Transport, Session, Presentation, Application.Match Layer 1 to “Physical.”Confirm scope: signaling and media only.
Verification / Alternative check:
Ethernet physicals (e.g., 1000BASE-T, 10GBASE-SR) and fiber standards are classic Layer-1 examples; MAC addressing belongs to Layer 2.
Why Other Options Are Wrong:
link layer: This is Layer 2 (Data Link).
Common Pitfalls:
Attributing error detection or media access to Layer 1; those are Layer-2 responsibilities.
Final Answer:
physical layer
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