ITPEC FE Subject A October 2024 Question 23

A repeater amplifies signals between segments of the same type — the only option that matches a LAN interconnection device with what it really works on.

• •Repeater — layer 1 (physical): regenerates and amplifies the signal so a cable segment can be extended; it does not look at any address
• •Bridge / layer 2 switch — layer 2 (data link): forwards frames by MAC address
• •Router — layer 3 (network): forwards packets by IP address
• •Gateway — layer 4 and above: converts protocols between networks with different protocol stacks, up to the application layer

Answer (c)

Why not others:

• •(a) — swaps the address type: a bridge relays frames by MAC address; relaying by IP address is a router's job
• •(b) — a gateway converts protocols at the upper layers (transport and above); a device limited to layers 1–3 is a router, not a gateway
• •(d) — swaps the address type the other way: a router relays packets by IP address, while relaying frames by MAC address is a bridge's job

Key rule: Repeater = layer 1 (signal), bridge/switch = layer 2 (MAC address), router = layer 3 (IP address), gateway = layer 4 and above (protocol conversion).

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