---
title: "Repeater, hub, bridge, switch, router"
subject: "Computer Networks and Security"
chapter: 3
key: "semester_7/computer_networks_and_security:network-devices-working"
source: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/network-devices-working
site: BCT Engineering
---

# Repeater, hub, bridge, switch, router

Computer Networks and Security · Chapter 3: Data Link Layer

- Asked in: 2070 Chaitra, 8 marks
- Video: [Network Devices Explained | Hub, Bridge, Router, Switch](https://www.youtube.com/watch?v=eMamgWllRFY) — CertBros
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/computer_networks_and_security/network-devices-working
- Whole chapter: https://www.bctengineer.com/md/semester_7/computer_networks_and_security/chapter-3

## Question

Explain the working principle of the different types of network devices: Repeater, HUB, Bridge, Switch and Router.

## Short answer

Repeater regenerates signals (Layer 1). Hub is a multiport repeater that broadcasts bits. Bridge and Switch operate at Layer 2, learning MAC addresses to forward frames selectively; Switch provides per-port collision domains. Router routes packets at Layer 3 using IP and routing tables.

## Answer

| Device | Layer | Works on |
|---|---|---|
| Repeater, Hub | Physical (1) | Bits / signals |
| Bridge, Switch | Data link (2) | Frames, MAC address |
| Router | Network (3) | Packets, IP address |

#### Repeater
A repeater regenerates and amplifies a weak signal so that it can travel farther than the cable's maximum length (for example, 100 m for UTP). It connects two segments of the same LAN, does not filter traffic and does not know addresses. It cleans up the signal, so noise is not carried over.

#### Hub
A hub is a multiport repeater (physical layer). A frame received on one port is **broadcast to all other ports**. All devices share the same collision domain and bandwidth, so performance falls as devices are added. Half duplex only.

#### Bridge
A bridge connects two LAN segments at the data link layer. It reads the source MAC address of each frame to build a **forwarding table** (learning) and forwards a frame only to the segment holding the destination MAC (filtering). Unknown or broadcast frames are flooded. It divides the collision domain into smaller ones, but not the broadcast domain.

#### Switch
A switch is a multiport bridge implemented in hardware. Each port is its own collision domain and gets dedicated bandwidth. It learns MAC addresses, keeps a MAC table and forwards a unicast frame only to the correct port. Supports full duplex, VLANs and microsegmentation. A layer-3 switch can route.

#### Router
A router connects different networks at the network layer. It reads the destination **IP address** and consults a **routing table** (built by RIP, OSPF, BGP) to select the best next hop. It separates broadcast domains, can perform NAT and fragmentation, and can filter traffic with access lists. It is used to connect a LAN to the Internet.

```text
 PC--[Switch]--[Router]--Internet
 PC--[Hub]----/
```

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does a hub do with a received frame?
   A. Sends only to the destination
   B. Broadcasts to all other ports in one collision domain
   C. Routes by IP
   D. Filters by MAC
   Answer: B. A hub is a multiport repeater with a single shared collision domain. (Key point: Hub)

2. How does a bridge build its forwarding table?
   A. By reading the source MAC address of frames
   B. By reading IP addresses
   C. By RIP
   D. Manually
   Answer: A. It learns source MACs and forwards only toward the segment holding the destination. (Key point: Bridge learning)

3. What distinguishes a switch port?
   A. All ports share one collision domain
   B. Each port is its own collision domain with dedicated bandwidth
   C. It separates broadcast domains
   D. It uses IP
   Answer: B. A switch is a hardware multiport bridge with per-port collision domains. (Key point: Switch)

4. Which device separates broadcast domains and uses a routing table?
   A. Hub
   B. Bridge
   C. Switch
   D. Router
   Answer: D. A router works at layer 3 with IP addresses and routing tables. (Key point: Router)

## Related in other subjects

- [Internet structure: repeater, bridge, router, gateway](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Ainternet-structure-devices) — Telecommunications, chapter 8
- [Working principle of a (vector) network analyzer](https://www.bctengineer.com/question.md?key=semester_7%2Frf_and_microwave_engineering%3Anetwork-analyzer-working) — RF and Microwave Engineering, chapter 8, asked 2×
- [Wien-bridge oscillator working](https://www.bctengineer.com/question.md?key=semester_3%2Felectronics_devices_and_circuit%3Awien-bridge-oscillator) — Electronics Devices and Circuit, chapter 5, asked 8×
- [Crossbar switch vs multistage network](https://www.bctengineer.com/question.md?key=semester_5%2Fcomputer_organization_and_architecture%3Acrossbar-vs-multistage) — Computer Organization and Architecture, chapter 8