Internet, Cybersecurity, and Network Fundamentals
Understanding Core IT Concepts
The Internet is a global network of interconnected computers and devices that communicate with each other using standardized communication protocols (like TCP/IP). It allows users to access and share information, communicate, stream media, do business, and much more from anywhere in the world.
Types of Internet Connections
Here are the main types of internet connections, each differing in speed, cost, and method of access:
Dial-Up Connection
- Medium: Telephone line
- Speed: Very slow (up to 56 kbps)
- Use: Older technology, mostly obsolete now
- How it works: Connects to the internet via a modem and phone line. You cannot use the phone while connected.
Broadband Connection
Broadband is a high-speed internet connection. It includes:
DSL (Digital Subscriber Line)
- Uses existing telephone lines
- Faster than dial-up
- Allows internet and phone use simultaneously
Cable
- Uses cable TV lines
- Offers high-speed internet
- Shared bandwidth with neighbors may slow it down during peak hours
Fiber-Optic (FTTH)
- Uses light signals through glass fibers
- Fastest type of broadband connection
- Ideal for streaming, gaming, and businesses
Wireless Connection (Wi-Fi)
Mobile Internet
Satellite Internet
Leased Line
Cybersecurity: Protecting Digital Assets
Cybersecurity refers to the practice of protecting computers, servers, mobile devices, networks, and data from malicious attacks, damage, or unauthorized access. It is also known as information technology security or computer security.
Objectives of Cybersecurity (CIA Triad)
- Confidentiality – Ensuring that information is not accessed by unauthorized people.
- Integrity – Ensuring data is not altered or tampered with.
- Availability – Ensuring data and systems are available to authorized users when needed.
Types of Cybersecurity
- Network Security
- Information Security
- Application Security
- Endpoint Security
- Cloud Security
- Operational Security (OPSEC)
Common Cyber Threats
| Threat Type | Description |
|---|---|
| Malware | Malicious software like viruses, worms, trojans |
| Phishing | Fake emails or messages tricking users to give up personal info |
| Ransomware | Locks or encrypts data and demands ransom |
| Denial of Service (DoS/DDoS) | Floods a server with traffic to crash it |
| Man-in-the-Middle Attack | Hacker intercepts communication between two parties |
| SQL Injection | Injects malicious SQL into a database query |
| Zero-Day Exploit | Attacks software before developers can fix a flaw |
Cybersecurity Tools & Techniques
- Antivirus software
- Firewalls
- Encryption (SSL, TLS)
- Two-factor authentication (2FA)
- Biometric security (fingerprint, face ID)
- Regular software updates & patches
- Backup and recovery solutions
- Security audits and penetration testing
Computer Networks: Connecting Devices
A computer network is a system that connects two or more computing devices to share resources and information. It enables devices to communicate and exchange data with each other, whether they are in the same room or across the globe. This is achieved through a combination of hardware and software, using wired or wireless connections and agreed-upon protocols.
How Computer Networks Work
- Connecting Devices: Devices (nodes) like computers, printers, or servers are connected using physical media (cables like Ethernet or fiber optic, or wireless like Wi-Fi).
- Defining Communication Rules (Protocols): Communication protocols, like TCP/IP, define how data is transmitted, formatted, and interpreted.
- Data Transmission: When a device wants to send data, it breaks it down into smaller packets, adds addressing information (IP address), and sends it through the network.
- Routing: Devices like routers examine the address and forward the data packets along the most efficient path to their destination.
- Reassembly: At the receiving end, the device reassembles the data packets into the original information.
Network Diagram Explanation
A simple network diagram might show:
- Nodes: Computers, printers, servers, etc., represented by icons.
- Connections: Lines representing physical cables or wireless connections between the devices.
- Central Device (optional): A hub, switch, or router that manages traffic and connections.
Network Topology: Arrangement of Devices
Network Topology refers to the physical or logical arrangement of computers, cables, and other components in a computer network. It shows how devices (nodes) are connected and how data flows within the network.
Types of Network Topologies
| Topology | Description |
|---|---|
| Bus | All devices are connected to a single central cable (backbone). |
| Star | All devices are connected to a central device (like a switch or hub). |
| Ring | Each device is connected to two others, forming a circular data path. |
| Mesh | Every device is connected to every other device. |
| Tree | A mix of star and bus; hierarchical in structure. |
| Hybrid | Combination of two or more topologies (e.g., star + mesh). |
Comparison of Network Topologies
| Feature | Bus | Star | Ring | Mesh | Tree | Hybrid |
|---|---|---|---|---|---|---|
| Structure | Single cable | Central device | Circular loop | Full connection | Hierarchical | Combination |
| Cost | Low | Medium | Medium | High | High | Varies |
| Reliability | Low | High | Medium | Very High | Medium | High |
| Cable Length | Least | More | Moderate | Most | High | Varies |
| Failure Impact | Entire network fails if backbone breaks | One device fails, rest work | Failure affects whole ring | No impact (redundancy) | Depends on level | Depends on topology used |
| Scalability | Low | High | Low | Low | High | High |
| Ease of Setup | Easy | Easy | Difficult | Complex | Complex | Complex |
Key Characteristics of Topologies
- Bus: Simple and cheap, but failure-prone.
- Star: Common and easy to manage; central device is crucial.
- Ring: Data flows in one direction; a break can affect all.
- Mesh: High reliability, expensive setup.
- Tree: Suitable for large organizations; follows hierarchy.
- Hybrid: Flexible and scalable; best for complex networks.
The World Wide Web (WWW): Accessing Information
The World Wide Web (WWW) is a system of interlinked hypertext documents and resources, accessed via the Internet using web browsers. It allows users to view and interact with websites containing text, images, videos, and links.
How the World Wide Web Works
- User Enters URL: A user types a URL (e.g., https://www.google.com) in the browser.
- DNS Lookup: The browser contacts a DNS (Domain Name System) server to convert the domain name (e.g., www.google.com) into an IP address of the web server.
- Request Sent to Web Server: The browser sends an HTTP/HTTPS request to the server at that IP address, asking for the web page.
- Web Server Responds: The web server processes the request and sends back the HTML page, along with CSS, JavaScript, and media files.
- Browser Displays the Page: The browser interprets the code and displays the formatted web page to the user.
Key Components of the World Wide Web
| Component | Description |
|---|---|
| Web Browser | Software used to access web pages (e.g., Chrome) |
| Web Server | Hosts websites and sends pages on request |
| Web Pages | Documents written in HTML, often linked together |
| HTTP/HTTPS | Protocols used to request and transmit web pages |
| URL | Address of a web resource (e.g., https://…) |
| DNS | Translates domain names into IP addresses |
WWW Summary Points
- The WWW is a service that runs over the Internet.
- It uses web browsers, servers, HTTP/HTTPS protocols, and URLs.
- It enables users to access information in the form of linked web pages.