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SSC CGL Preparation – Day 8
Computer Basics: Ports
📌 What is a Port in Computers?
A port in a computer is a physical or virtual interface through which data is sent or received. Ports allow various devices to connect to the computer to either transfer data or allow communication between devices.
There are two main types of ports:
- Hardware (Physical) Ports
- Software (Logical/Network) Ports
🔌 1. Physical Ports (Hardware Ports)
These are actual connectors on your computer or laptop that allow peripheral devices (mouse, keyboard, printer, etc.) to connect.
📚 Common Physical Ports:
| Port Name | Description | Common Use |
|---|---|---|
| USB (Universal Serial Bus) | Most widely used port today | Connects flash drives, keyboards, phones, printers, etc. |
| HDMI (High-Definition Multimedia Interface) | Transmits high-definition audio and video | Connects monitors, projectors, TVs |
| VGA (Video Graphics Array) | Analog video port | Used in older monitors and projectors |
| Ethernet (RJ-45) | Wired network connection | Connects to LAN (Local Area Network) |
| Audio Jack (3.5 mm) | Used for audio input/output | Headphones, microphones, speakers |
| Serial Port (COM port) | Transmits data one bit at a time | Old modems, mouse (mostly outdated) |
| Parallel Port (LPT) | Transmits multiple bits at once | Older printers, scanners |
| Thunderbolt / USB-C | High-speed multi-use port | Used in newer devices for charging, display, and data transfer |
| PS/2 Port | Round connectors for keyboard/mouse | Used in older desktop systems |
🌐 2. Logical Ports (Software or Network Ports)
These ports are virtual endpoints for network communications. They are used by applications and protocols to communicate over the internet or a local network.
📚 Common Logical/Network Ports and Their Functions:
| Port Number | Protocol | Description |
|---|---|---|
| 20 & 21 | FTP (File Transfer Protocol) | Used for file transfers |
| 22 | SSH (Secure Shell) | Remote login securely |
| 23 | Telnet | Remote login (not secure) |
| 25 | SMTP (Simple Mail Transfer Protocol) | Sending emails |
| 53 | DNS (Domain Name System) | Resolving domain names to IP |
| 80 | HTTP (HyperText Transfer Protocol) | Web browsing (insecure) |
| 443 | HTTPS (HTTP Secure) | Secure web browsing |
| 110 | POP3 (Post Office Protocol) | Receiving emails |
| 143 | IMAP (Internet Message Access Protocol) | Retrieving emails |
| 3389 | RDP (Remote Desktop Protocol) | Remote desktop access |
📖 Note: Logical ports range from 0 to 65535. The first 1024 ports are called well-known ports.
🧠 Key Points to Remember
- USB ports come in different versions: USB 1.0, 2.0, 3.0, 3.1, and USB-C.
- HDMI supports both video and audio, while VGA supports only video.
- RJ-45 ports connect to LAN via an Ethernet cable.
- PS/2 ports are circular and color-coded: purple for keyboards, green for mice.
- Logical ports help manage communication between applications on a network.
🧪 Exam Tips
- Focus on common port numbers: 21 (FTP), 25 (SMTP), 80 (HTTP), 443 (HTTPS).
- Know the difference between physical and logical ports.
- Identify ports by shape and function for physical ones (e.g., USB, HDMI, VGA).
- USB 3.0 ports are often blue in color and faster than USB 2.0.
