أساسيات الشبكات - القسم 1

Network Basics

• A network is a collection of interconnected devices, such as computers, printers, and servers, that can communicate with each other. These devices share resources and information.
• Networks are crucial for communication and data sharing, enabling distributed computing, remote access, and collaborative work among users.
• Various types of networks exist, varying in size and capabilities, from local area networks (LANs) to wide area networks (WANs) and the global internet.

Network Topologies

• Bus topology: A single cable connects all devices, with signals traveling the length of the cable. If a break occurs in the cable, the entire network can be disrupted.
• Star topology: All devices connect to a central hub or switch. Data passes through the central point to reach its destination. Easier to troubleshoot than a bus.
• Ring topology: Devices are connected in a closed loop, with signals traveling in one direction. A break in the ring disrupts the entire network.
• Mesh topology: Devices are interconnected with multiple paths. Redundancy is a key feature; breaks in one connection do not affect the entire network.
• Tree topology: Combines elements of star and bus topologies, forming a hierarchical structure.

Network Protocols

• Protocols are sets of rules that govern how data is transmitted and received across a network. Different protocols handle different tasks, from data transmission to error detection and correction.
• TCP/IP (Transmission Control Protocol/Internet Protocol): The foundational protocol suite for the internet and many other networks. Handles reliable data transmission, ordering, and error correction.
• HTTP (Hypertext Transfer Protocol): Used for transferring web pages and other data over the internet, primarily for communication between web browsers and web servers.
• FTP (File Transfer Protocol): A protocol for transferring files between computers over a network.
• IP (Internet Protocol): Handles addressing and routing data packets across networks. Unique IP addresses identify devices on the network.
• DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses to devices on a network. Simplifies network administration and reduces configuration errors.

Network Devices

• Routers: Connect different networks together and forward data packets between them. They determine the best path for data transmission.
• Switches: Connect devices within a local network. Switches forward data only to the intended recipient, improving network performance compared to a hub.
• Hubs: Simple devices that broadcast data to all connected devices. Less efficient than a switch due to a lack of addressing.
• Modems: Connects a network to an external network, like the internet, using a communication channel. Converts data between digital and analog formats.
• Network Interface Card (NIC): A physical interface card that allows a computer to connect to a network. Provides a physical connection point.

Network Security

• Security is vital to protect sensitive data and prevent unauthorized access or malicious activities.
• Firewalls: Security systems that control incoming and outgoing network traffic based on predefined rules. Prevent unauthorized access and protect the network from malicious threats.
• Encryption: A method to scramble data in transit, preventing unauthorized disclosure. Vital for secure communication over networks.
• Access Control: Restricting access to a network to authorized users, preventing unauthorized users from accessing critical resources.
• Passwords, Authentication and Authorization: Utilizing strong passwords and multi-factor authentication, and controlling permission access limits, are critically important for network security.

Network Models

• OSI Model (Open Systems Interconnection Model): A conceptual framework that enables different networking systems to communicate. It breaks down network communication tasks into seven layers.
• TCP/IP Model: A practical implementation of networking protocols. Focuses on application, transport, internet, and network access layers. Easier to implement than OSI.

Network Performance

• Bandwidth refers to the rate at which data can be transmitted over a network.
• Latency, or delay, is the time it takes for data to travel across a network.
• Network congestion occurs when the network's capacity is exceeded. This leads to delays and reduced performance of the network. Appropriate network design is essential to handle peak use cases and data volume.