ITPEC FE Morning October 2019 Question 32
Which of the following is the device that operates only at the physical layer of the OSI model?
Explanation
Repeater — it regenerates and amplifies the electrical signal and reads no address, so it works only at the physical layer (layer 1).
A repeater extends the length of a cable segment by restoring the bits it receives and sending them on unchanged. It does not know about frames or packets; a repeater hub is the same device with several ports.
Answer (b)
Why not others:
- •(a) Bridge — layer 2: it relays frames between segments by their destination MAC address
- •(c) Router — layer 3: it forwards packets between networks by their IP address
- •(d) Switch — a layer 2 device (a multiport bridge) that sends each frame only to the port of its destination MAC address
Key rule: Place a device by the highest header it reads: none is layer 1 (repeater, hub), MAC address is layer 2 (bridge, switch), IP address is layer 3 (router).
Networks · AI-written, may contain errors
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