Connecting computers needs hardware (the devices that move and direct data) and protocols (the agreed rules that let different machines understand each other). Get these names and roles straight — they're among the most frequently tested topics in the networks unit.
1Network devices
| Device | What it does |
|---|---|
| NIC (Network Interface Card) | The hardware inside a device that connects it to a network; each has a unique MAC address. |
| Repeater | Regenerates (boosts) a weak signal so it can travel further. |
| Hub | Connects devices in a LAN but broadcasts data to all ports — simple and 'dumb'. |
| Switch | Like a hub but smart — sends data only to the intended device. More efficient. |
| Router | Connects different networks and chooses the best path for data (e.g. your home network to the Internet). |
| Gateway | Connects two networks that use different protocols — a translator between systems. |
| Modem | Modulator-Demodulator: converts digital data to analog signals for transmission (e.g. over phone lines) and back. |
Hub vs Switch: a hub shouts the message to everyone; a switch delivers it privately to the right recipient. That's why switches are used in modern networks.
Key points
- NIC connects a device to the network (has a MAC address); repeater boosts a weak signal.
- Hub broadcasts to all ports; switch sends only to the intended device (smarter, efficient).
- Router connects different networks and finds the best path; gateway connects networks using different protocols; modem converts digital ↔ analog.
2Protocols and IP addresses
A protocol is a set of rules that govern how data is sent and received. The key ones:
| Protocol | Used for |
|---|---|
| TCP/IP | The core suite of the Internet — TCP splits/reassembles data reliably, IP addresses and routes the packets. |
| HTTP / HTTPS | Transferring web pages. HTTPS is the secure (encrypted) version. |
| FTP | File Transfer Protocol — uploading/downloading files. |
| SMTP | Sending email. |
| POP3 | Receiving/retrieving email. |
| Telnet / SSH | Remote login to another computer. SSH is the secure (encrypted) version. |
| PPP | Point-to-Point Protocol — connecting two nodes directly. |
IP addresses: IPv4 vs IPv6
Every device on a network needs a unique IP address.
| IPv4 | IPv6 | |
|---|---|---|
| Size | 32-bit | 128-bit |
| Format | Four numbers, e.g. 192.168.1.1 | Eight hex groups, e.g. 2001:0db8:... |
| Addresses | ~4.3 billion (running out) | Vastly more (effectively unlimited) |
Key points
- A protocol is the set of rules for communication; TCP/IP is the Internet's core suite.
- HTTP/HTTPS = web pages (HTTPS secure), FTP = files, SMTP = send email, POP3 = receive email, Telnet/SSH = remote login (SSH secure).
- IPv4 is 32-bit (~4.3 billion addresses, e.g. 192.168.1.1); IPv6 is 128-bit with vastly more addresses.
3VoIP and wireless generations
- VoIP (Voice over Internet Protocol) — carries voice calls over the Internet instead of the traditional phone network (e.g. WhatsApp/Skype calls). Cheaper and uses packet switching.
- Wi-Fi — wireless networking using radio waves, letting devices join a LAN/Internet without cables.
Mobile generations
| Generation | Brought |
|---|---|
| 2G | Digital voice + basic texting (SMS) |
| 3G | Mobile internet, video calls |
| 4G | Fast broadband-speed data, streaming |
| 5G | Very high speed, very low delay (latency); supports IoT at scale |
Key points
- VoIP carries voice calls over the Internet using packet switching (e.g. WhatsApp calls).
- Wi-Fi connects devices to a network wirelessly via radio waves.
- Mobile generations: 2G (digital voice/SMS) → 3G (mobile internet) → 4G (fast data/streaming) → 5G (very fast, low latency, IoT).
★ Practical: match the tool to the job
Answer briefly:
- Which device sends data only to the intended recipient — a hub or a switch?
- Name the protocol used for: viewing a secure website, sending an email, transferring a file.
- State two differences between IPv4 and IPv6.
- Which device would connect your home network to the Internet, and which translates between two different-protocol networks?
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