Network Devices and Transmission Media: Hub, Switch, Router, Modem, Fibre Optic and Data Transmission Modes for SSC
Rahul Kumar
SSC Exam Expert & Content Editor
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PDF Notes: Network Devices and Transmission Media: Hub, Switch, Router, Modem, Fibre Optic and Data Transmission Modes for SSC
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Computers in a network are connected by devices and cables, and SSC computer awareness often asks about the function of a router or the fastest transmission medium. This guide on network devices and transmission media for SSC explains the main devices, the types of cables and wireless media, bandwidth and the modes of data transmission, with practice questions and FAQs.
Network Devices
| Device | Function |
|---|---|
| Hub | Connects several computers in a LAN and sends data to all connected computers (broadcast); a simple, unintelligent device |
| Switch | Connects devices in a LAN and sends data only to the device for which it is meant, using the MAC address; smarter than a hub |
| Bridge | Connects two LANs of the same protocol and filters traffic |
| Router | Connects different networks (such as a LAN with the Internet) and decides the best path for packets using the IP address |
| Gateway | Connects networks that use different protocols; works as a translator |
| Repeater | Regenerates and amplifies the signal to extend the range |
| Modem | Modulator-demodulator; converts digital signals into analog signals and back, for use on telephone lines |
| Network Interface Card (NIC) | Hardware that connects a computer to a network; has a unique MAC address |
| Access point | Allows wireless devices to connect to a wired network |
Transmission Media
Transmission media are the paths along which data travels. They are of two kinds: guided (wired) and unguided (wireless).
| Medium | Type | Features |
|---|---|---|
| Twisted pair (UTP, STP) | Guided | Two insulated copper wires twisted together; cheap; used in telephone lines and LANs |
| Coaxial cable | Guided | A copper core with shielding; used in cable TV; higher bandwidth than twisted pair |
| Optical fibre | Guided | Thin glass or plastic fibre that carries data as light pulses; fastest, most secure and least affected by interference; used for broadband |
| Radio waves | Unguided | Used in radio, Wi-Fi and mobile networks |
| Microwaves | Unguided | Line-of-sight; used for long-distance communication |
| Infrared | Unguided | Short range; used in remote controls |
| Satellite | Unguided | Used for TV, GPS and remote communication |
Modes of Data Transmission
| Mode | Meaning | Example |
|---|---|---|
| Simplex | Data flows in one direction only | Keyboard to computer, radio broadcast, television |
| Half duplex | Data flows in both directions, but only one at a time | Walkie-talkie |
| Full duplex | Data flows in both directions at the same time | Telephone call, mobile phone |
Bandwidth and Speed
- Bandwidth is the amount of data that can be sent through a medium in a given time.
- The unit of data transfer rate is bits per second (bps); larger units are Kbps, Mbps and Gbps.
- Latency is the delay in the transmission of data.
- 1 byte = 8 bits, so a speed of 8 Mbps equals 1 MB per second.
- Optical fibre gives the highest bandwidth and speed among the guided media.
Comparison of Hub, Switch and Router
| Feature | Hub | Switch | Router |
|---|---|---|---|
| Works on | Physical layer | Data link layer | Network layer |
| Sends data to | All devices | Specific device (MAC address) | Another network (IP address) |
| Intelligence | None | Medium | High |
| Use | Connect devices in a small LAN | Connect devices in a LAN | Connect networks and the Internet |
Important Facts
- Optical fibre is the fastest and most secure wired medium.
- A router connects a home network to the Internet service provider.
- The MAC address is a 48-bit hardware address, while an IP address is a logical address.
- Bluetooth works over short ranges using radio waves.
- A modem is needed to convert digital data into analog for a telephone line.
Quick Tips
- Learn each device with its one-line function.
- Remember that fibre optic is the fastest medium.
- Remember hub: broadcast; switch: specific device; router: between networks.
- Learn the three transmission modes with examples.
Quick Revision Points
- Router connects different networks.
- Switch uses MAC addresses; router uses IP addresses.
- Modem converts digital signals into analog and back.
- Optical fibre uses light pulses and is the fastest wired medium.
- Full duplex allows two-way communication at the same time.
Practice Questions With Answers
- Which device connects different networks and chooses the best path?
Answer: Router - Which medium is the fastest and uses light?
Answer: Optical fibre - Which device converts digital signals into analog signals?
Answer: Modem - Which mode allows two-way communication at the same time?
Answer: Full duplex - Which device sends data to all connected computers?
Answer: Hub - Which device uses the MAC address to send data to a specific computer?
Answer: Switch - A walkie-talkie works in which mode?
Answer: Half duplex - Which device connects networks with different protocols?
Answer: Gateway - What is the unit of data transfer speed?
Answer: Bits per second (bps) - Which device amplifies a weak signal?
Answer: Repeater
How to Practise This Chapter
Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Computer Knowledge notes page, read the previous topic Logic Gates and Boolean Algebra.
Frequently Asked Questions
What is a router?
A device that connects different networks and forwards data packets using IP addresses.
What is the difference between a hub and a switch?
A hub sends data to all devices, while a switch sends it only to the intended device.
What does a modem do?
It converts digital data into analog signals for transmission and back.
What is a gateway?
A device that connects networks using different protocols.
What is the fastest transmission medium?
Optical fibre.
What is twisted pair cable?
A cable with pairs of copper wires twisted together, used for telephone lines and LANs.
What is simplex mode?
One-way communication, as in television broadcast.
What is full duplex?
Two-way communication at the same time, such as a phone call.
What is bandwidth?
The amount of data that can be transmitted in a given time.
What is a NIC?
A network interface card that connects a computer to a network.
What is a repeater?
A device that regenerates and strengthens signals.
Is this topic asked in SSC?
Yes. Network devices and media are common in the computer awareness section.
Rahul Kumar
SSC Exam Expert & Content Editor
Rahul is a senior SSC exam strategist with 8+ years of experience helping aspirants crack CGL, CHSL and MTS exams. He writes in-depth notification breakdowns, exam pattern guides and preparation strategies.