Networks and The Internet

The OSI Model is a conceptual, implementation-neutral model that describes networking in seven separate layers, where each layer covers a set of functions and tasks.

This model helps us communicate while we do network troubleshooting and architecture.

The TCP/IP Model is an implementation-specific networking model that revolves around the TCP protocol and IP addressing which anchor the Internet as we know it.

Its layers include:

• The Network Layer
• The Internet Layer
• The Transport Layer
• The Application Layer

The OSI layers include: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• The Physical layer includes physical technologies
• The Data Link layer includes data framing and local MAC addressing
• The Network layer includes connecting to the larger web and IP addressing
• The Transport layer includes protocols that make sure reliable delivery happens
• The Session layer authenticates and maintains communication over a period of time
• The Presentation layer en/decrypts and translates data into presentable form
• The Application layer includes all the applications we interact with that render data

Three broad categories of networks include:

• Local Area Network (LAN), a smaller-sized network that connects multiple devices in a small area
• Campus Area Network (CAN), a larger network that connects multiple computers and devices over a slightly larger area
• Wide Area Network (WAN), the largest-sized network that connects multiple computers, over a geographically large area

The Internet is technically a WAN.

A network is two or more computers or devices that are linked in order to share information.

Networking refers to a large set of standards and protocols that organize and regulate the sharing of information.

A network protocol is a set of standards for Internet traffic.

Among them are the big transport protocols:

• TCP and UDP
• HTTP for web requests
• DNS to convert domain names to IP addresses
• IMAP/POP3 for email
• SSH
• FTP
• SMB for access to specific resources