Network Fundamentals and Routing Protocols

Definition: Understanding how networks operate, including devices and protocols.
Types of Networks:
- LAN (Local Area Network)
- WAN (Wide Area Network)
- MAN (Metropolitan Area Network)
Network Topologies:
- Star, Mesh, Bus, Ring
OSI Model: 7 Layers (Physical, Data Link, Network, Transport, Session, Presentation, Application)
TCP/IP Model: 4 Layers (Link, Internet, Transport, Application)
Devices:
- Routers: Connect different networks, route data.
- Switches: Connect devices within a network, operate at Layer 2.
- Hubs: Basic device for connecting multiple Ethernet devices.

Purpose: Determine the best path for data to travel across networks.
Types:
- Static Routing: Manually configured routes; no automatic updates.
- Dynamic Routing Protocols:
  - RIP (Routing Information Protocol): Distance-vector protocol; uses hop count.
  - OSPF (Open Shortest Path First): Link-state protocol; uses cost based on bandwidth.
  - EIGRP (Enhanced Interior Gateway Routing Protocol): Hybrid protocol; combines features of both distance-vector and link-state.
Routing Tables: Maintain routes to different networks; updated dynamically by routing protocols.

Function: Connect devices within the same network segment.
Types of Switching:
- Circuit Switching: Dedicated path for the duration of the connection.
- Packet Switching: Data divided into packets; sent independently.
Ethernet: Most common LAN technology; operates at Layer 2.
VLANs (Virtual Local Area Networks): Segment network traffic, improve security and performance.
Spanning Tree Protocol (STP): Prevent loops in switched networks.

IP Address: Unique identifier for devices on a network.
IPv4: 32-bit address; format: xxx.xxx.xxx.xxx.
- Classes: A, B, C, D, E (Class A for large networks, Class C for smaller).
Subnetting: Dividing a network into smaller sub-networks to improve management and security.
CIDR (Classless Inter-Domain Routing): More efficient IP address allocation; format: xxx.xxx.xxx.xxx/xx.
IPv6: 128-bit address; hexadecimal format; designed to replace IPv4.

Importance: Protecting data and resources from unauthorized access and attacks.
Key Concepts:
- Firewalls: Control incoming and outgoing network traffic based on security rules.
- VPN (Virtual Private Network): Secure connection over the internet, encrypts data.
- Access Control Lists (ACLs): Define permissions for users and devices on a network.
Security Protocols:
- HTTPS: Secure version of HTTP, encrypts data in transit.
- SSH (Secure Shell): Secure network protocol for remote access.
Threats:
- Malware, phishing, DDoS attacks, man-in-the-middle attacks.

Networks consist of interconnected devices that communicate using various protocols.
Local Area Network (LAN) covers small geographical areas, typically a single building.
Wide Area Network (WAN) spans large geographical areas, connecting multiple LANs.
Metropolitan Area Network (MAN) serves a city or large campus, bridging LANs and WANs.
Network topologies define the layout of devices: Star, Mesh, Bus, and Ring configurations are common.
The OSI Model comprises seven layers (Physical, Data Link, Network, Transport, Session, Presentation, Application) that standardize network communication.
The TCP/IP Model has four layers (Link, Internet, Transport, Application) and is integral to the internet's architecture.
Routers facilitate data routing between different networks, while switches connect devices within a single network segment at Layer 2.
Hubs are basic devices used to connect multiple Ethernet devices but lack intelligence compared to switches.

Routing protocols are designed to identify the most efficient path for data transmission across networks.
Static Routing requires manual configuration and remains fixed; it does not adapt to changes.
Routing Information Protocol (RIP) operates as a distance-vector protocol based on hop count for path determination.
Open Shortest Path First (OSPF) is a link-state protocol that calculates paths based on bandwidth cost, enhancing routing efficiency.
Enhanced Interior Gateway Routing Protocol (EIGRP) integrates both distance-vector and link-state functionalities for dynamic path-finding.
Routing tables are essential for maintaining and updating available paths to different networks.

Switching provides connectivity among devices within the same network, ensuring efficient communication.
Circuit Switching establishes a dedicated communication path for the duration of a session.
Packet Switching breaks data into packets for individual, independent transfers, optimizing network usage.
Ethernet is the predominant technology for Local Area Networks, functioning at Layer 2.
Virtual Local Area Networks (VLANs) help segregate network traffic to enhance security and performance.
Spanning Tree Protocol (STP) is crucial for preventing loops in networks that use multiple switches.

An IP Address serves as a unique identifier for devices in a network, essential for routing.
IPv4 uses a 32-bit addressing scheme, formatted as xxx.xxx.xxx.xxx, with established classes for different sized networks (A, B, C, D, E).
Subnetting partitions a larger network into smaller sub-networks, improving management and security.
Classless Inter-Domain Routing (CIDR) optimizes IP address allocation through a format of xxx.xxx.xxx.xxx/xx.
IPv6 introduces a 128-bit addressing format using hexadecimal, aimed at addressing the limitations of IPv4.

Network security is critical for safeguarding data and resources from unauthorized access and cyber threats.
Firewalls are essential tools for controlling the flow of network traffic based on predefined security rules.
Virtual Private Networks (VPNs) provide secure, encrypted connections over the internet to protect data integrity.
Access Control Lists (ACLs) specify user and device permissions, enhancing security within networks.
Security protocols like HTTPS ensure data encryption in transit, while SSH secures remote access protocols.
Cybersecurity threats include malware, phishing, Distributed Denial of Service (DDoS) attacks, and man-in-the-middle attacks.