Regarding Computer Networking in buildings:1.A Star topology is the most common configuration for office Local Area Networks (LAN).2.Fiber optic cables are preferred for long-distance building backbones due to their high bandwidth and immunity to EMI.3.A Switch operates at the Physical layer (Layer 1) of the OSI model.Which of the statements given above is/are correct?

Correct Answer: D - 1 and 2 only

Quick Concept Explanation

Modern office/building LANs commonly use switched Ethernet in a star topology. Fiber is favored for high-bandwidth or long backbone links and for immunity to electromagnetic interference. Key relation: Ethernet switch: primarily Layer 2; fiber backbone: high bandwidth and EMI immunity.

Exam focus: Distinguish a switch from a hub/repeater in OSI-layer questions. Common trap: A normal Ethernet switch is not principally a Layer-1 device.

Statement-wise Verification

• Statement 1 - Correct.
  A Star topology is the most common configuration for office Local Area Networks (LAN).
  Modern office/building LANs commonly use switched Ethernet in a star topology.
• Statement 2 - Correct.
  Fiber optic cables are preferred for long-distance building backbones due to their high bandwidth and immunity to EMI.
  Ethernet switch: primarily Layer 2; fiber backbone: high bandwidth and EMI immunity.
• Statement 3 - Incorrect.
  A Switch operates at the Physical layer (Layer 1) of the OSI model.
  A standard Ethernet switch is primarily a Layer-2 data-link device, although multilayer switches also exist

Core Concept

Modern office/building LANs commonly use switched Ethernet in a star topology. Fiber is favored for high-bandwidth or long backbone links and for immunity to electromagnetic interference. A conventional Ethernet switch makes forwarding decisions primarily at OSI Layer 2 using MAC addresses, whereas repeaters/hubs are Layer-1 devices.

Formula / Key Relationship

Ethernet switch: primarily Layer 2; fiber backbone: high bandwidth and EMI immunity.

Why the Other Options Are Wrong

Option A is incorrect because it includes incorrect statement(s) 3. Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option C is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 2.

Exam Shortcut / Approach

Distinguish a switch from a hub/repeater in OSI-layer questions.

Common Mistake

A normal Ethernet switch is not principally a Layer-1 device.

Quick Revision

Star LAN Fiber Backbone and Ethernet Switch is linked with Network Topology and Media, LAN and Building Networks and Computer Networks. Distinguish a switch from a hub/repeater in OSI-layer questions.