Computer Operator Loksewa Preparation
Computer Networking — Complete Notes
Covers: Network Types · Topologies · Cables · Devices · IP Addressing · Commands · Internet · Cloud
1. Definition of Networking
Networking is the process of connecting multiple devices — computers, servers, smartphones — to share resources, data, and communication. It enables efficient collaboration across personal, business, and government settings.
2. Types of Networks
A. Based on Geographical Scope
| Type | Full Form | Description | Example |
|---|---|---|---|
| PAN | Personal Area Network | Connects personal devices within short range | Bluetooth, USB Tethering |
| LAN | Local Area Network | Covers homes, offices, or schools | Office Wi-Fi, School Labs |
| MAN | Metropolitan Area Network | Covers a city, connects multiple LANs | ISP networks in a city |
| WAN | Wide Area Network | Covers large geographical areas | The Internet, VPN |
| WLAN | Wireless LAN | LAN using Wi-Fi instead of wired connections | Office/home Wi-Fi |
| SAN | Storage Area Network | Dedicated network for storing data | Cloud Storage Centers |
| VPN | Virtual Private Network | Secure encrypted connection over public network | Remote company access |
B. Based on Functionality
Client-Server
Central server manages resources; clients request services.
Peer-to-Peer (P2P)
Computers share resources directly without a central server.
Cloud Network
Uses cloud computing for networking. E.g. Google Drive, OneDrive.
Enterprise Network
Large-scale private network for organizational communication.
3. Network Topologies
Network topology refers to the physical or logical arrangement of devices in a network.
| Topology | Description | Advantages | Disadvantages |
|---|---|---|---|
| Bus | All devices share a single communication line | Simple and cost-effective | Whole network fails if main cable fails |
| Star | All devices connected to a central hub/switch | Easy to troubleshoot and expand | Network fails if central hub fails |
| Ring | Devices connected in a circular loop | Reduces data collisions | Single failure can break the network |
| Mesh | Each device connected to multiple devices | High redundancy and reliability | Expensive and complex to set up |
| Tree | Combination of bus and star topology | Scalable and hierarchical | Failure of main cable affects segments |
| Hybrid | Mix of two or more topologies | Flexible and efficient | High cost and complexity |
4. Network Cables and Connectors
A. Wired Cables
| Cable Type | Description | Speed & Distance | Usage |
|---|---|---|---|
| Twisted Pair | Pairs of wires twisted to reduce interference | 10 Mbps – 10 Gbps, up to 100m | LAN, office networks |
| Coaxial | Single copper core with shielding | Up to 10 Mbps, up to 500m | Cable TV, broadband |
| Fiber Optic | Uses light signals for high-speed data | 100 Mbps – 100 Gbps, up to 100 km | ISPs, long-distance networks |
B. Wireless Media
C. Network Connectors
| Connector | Description | Used For |
|---|---|---|
| RJ-45 | Standard connector for Ethernet cables | LAN connections |
| RJ-11 | Smaller connector for telephone lines | Dial-up internet |
| BNC | Connector for coaxial cables | Old Ethernet, CCTV systems |
| SC & LC | Fiber optic connectors for high-speed data | Long-distance networking |
| USB | Universal Serial Bus connector | USB modems and routers |
5. Network Devices
| Device | Description | Function / Usage |
|---|---|---|
| Hub | Broadcasts data to all connected devices | Used in small networks; less efficient |
| Switch | Sends data only to the intended device | Improves network performance and efficiency |
| Router | Connects different networks, manages internet traffic | Connects local network to the internet |
| Gateway | Connects two different network types and protocols | Enterprise networks, cloud services |
| Modem | Converts digital ↔ analog signals for internet access | DSL, fiber, and cable internet |
| Repeater | Amplifies weak signals to extend network range | Long-distance communication |
| Access Point | Provides wireless connectivity to a network | Wi-Fi networks |
| Firewall | Filters incoming and outgoing traffic | Protects against cyber threats |
6. Cable Testing
After installation, cables must be tested to ensure proper data transmission.
Checks continuity, wiring errors, and signal strength.
Advanced tool for network diagnostics.
Helps locate cables in walls and patch panels.
Identifies network performance issues.
Common Cable Issues and Fixes
| Problem | Cause | Fix |
|---|---|---|
| No connection | Loose or broken wires | Check cable continuity |
| Slow speed | Poor-quality cable or interference | Use shielded cables and proper routing |
| Data loss | Faulty connectors | Re-crimp and test connectors |
7. IP Addressing
An IP address is a unique identifier assigned to each device in a network.
Types of IP Addresses
| Type | Example | Description |
|---|---|---|
| IPv4 | 192.168.1.1 | Most common format; 32-bit address |
| IPv6 | 2001:db8::ff00:42:8329 | Future-proof; 128-bit; supports more devices |
| Public IP | Assigned by ISP | Used to connect to the internet |
| Private IP | 192.168.x.x / 10.x.x.x | Used within LAN networks |
Subnet Mask
Determines network vs host portion. Example: 255.255.255.0 (Class C)
Default Gateway
Connects local network to external networks. E.g. 192.168.1.1
DNS
Translates domain names to IPs. Google: 8.8.8.8 · Cloudflare: 1.1.1.1
Static vs Dynamic IP
Static: Manually set, fixed (servers, printers).
Dynamic: Auto-assigned by DHCP server.
8. Network Utility Commands
9. E-Mail, Internet, and WWW
E-Mail (Electronic Mail)
A digital method of sending messages and files over the internet.
- SMTP (Simple Mail Transfer Protocol) — Sends emails
- POP3 / IMAP — Retrieves emails
- Providers: Gmail, Outlook, Yahoo Mail
Internet
A global network connecting millions of devices using TCP/IP protocols. Provides web browsing, email, VoIP, cloud computing, and online gaming.
Intranet vs. Extranet
| Feature | Intranet | Extranet |
|---|---|---|
| Definition | Private network within an organization | Private network accessible by external users |
| Access | Employees only | Partners, suppliers, selected users |
| Example | Internal HR and payroll portals | Vendor portals, supply chain management |
World Wide Web (WWW)
- A service that runs on the internet using HTTP/HTTPS
- Websites accessed via browsers: Chrome, Firefox, Edge
- Built with HTML, CSS, JavaScript
- Search Engines: Google, Bing, DuckDuckGo
10. Web Browsers
A web browser is a software application used to access and navigate the World Wide Web.
| Browser | Developer | Key Features |
|---|---|---|
| Google Chrome | Fast browsing, extensions, Incognito mode | |
| Mozilla Firefox | Mozilla Foundation | Privacy-focused, open-source, customizable |
| Microsoft Edge | Microsoft | Windows integration, Read Aloud, Collections |
| Safari | Apple | Optimized for macOS/iOS, privacy protection |
| Opera | Opera Software | Built-in VPN, ad blocker, speed dial |
| Brave | Brave Software | Privacy-focused, no ads, built-in crypto wallet |
Features of Modern Browsers
11. Cloud Computing
Cloud computing allows users to store and access data over the internet instead of on local devices, offering on-demand storage, computing power, and application hosting.
| Service | Provider | Key Features |
|---|---|---|
| Google Drive | File storage, integrates with Google Docs & Gmail | |
| Dropbox | Dropbox Inc. | File sharing, storage and backup service |
| iCloud | Apple | Stores and syncs iPhone, iPad, and Mac data |
| OneDrive | Microsoft | Stores Office files, integrated with Windows |
| AWS | Amazon | Cloud storage, AI, virtual machines (EC2, S3) |
| Google Cloud (GCP) | Cloud hosting, machine learning, big data |
Benefits of Cloud Services
ping, ipconfig, tracert, and nslookup.
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