## What is a Network? - **Connectivity**: Enables communication paths between devices and networks. - **Data Transmission**: Transfers data using routing (inter-network) and switching (intra-network). - **Protocols**: Ensure data is transmitted correctly and securely (e.g., TCP/IP, HTTP). - **Security**: Implements firewalls, encryption, and access controls to protect data. --- ## Key Network Components - **Routers**: Direct data between networks; use IP addresses to forward packets. - **Switches**: Manage data within local networks based on MAC addresses. - **Firewalls**: Monitor and control traffic using security rules. - **Wireless Access Points**: Connect wireless devices to a wired network. - **Intermediaries**: Load balancers, reverse proxies, and bastion hosts enhance performance and security. --- ## Network Topologies - **Bus**: Shared communication line; cost-effective but limited performance. - **Star**: Devices connect to a central hub; isolates faults effectively. - **Ring**: Circular connection; efficient but can fail without redundancy. - **Mesh**: Multiple connections; highly reliable but costly. - **Hybrid**: Combines topologies for specific needs. --- ## Levels of Abstraction - **Physical Layer**: Hardware like cables, switches and routers. - **Virtual Network Layer**: Isolated network segments (e.g., VLANs, VPNs). - **Cloud Network Layer**: Managed solutions like Azure VNets and AWS VPCs. - **Serverless Networking**: Automated routing and scaling by cloud providers. --- ## Network Security - **Firewalls**: Block unauthorized access. - **Encryption**: Protects data in transit. - **Intrusion Detection Systems (IDS)**: Monitor for suspicious activity.