Network protocols are rules or standards that define how data is transmitted across networks. Each protocol operates at different layers of the OSI or TCP/IP models and serves a specific function in the communication process. Let's dive into the some of the most common network protocols: HTTP, FTP, DNS, and DHCP.

HTTP (HyperText Transfer Protocol):

• Layer: Application Layer (OSI), Application Layer (TCP/IP)
• Function: HTTP is the protocol used for transferring web pages and web resources over the internet.
• Purpose: It defines how clients (like web browsers) request web pages from servers, and how servers send the data back to the clients.

Key Features of HTTP:

• Stateless: HTTP doesn’t retain any memory of previous requests. Each request is independent, meaning the server doesn’t remember any data from prior interactions.
• Request/Response Model: Clients send HTTP requests to servers, and servers return HTTP responses. The response typically contains HTML content, images, or other web resources.

Common HTTP methods include:

• GET: Request data from a server.
• POST: Send data to a server (usually for form submissions).
• PUT: Replace data on the server.
• DELETE: Remove data from the server.
• HEAD: Similar to GET, but only retrieves headers.

Example HTTP Request:

GET /index.html HTTP/1.1
Host: www.example.com

This requests the index.html file from [www.example.com](<http://www.example.com/>).

Secure Version: HTTPS (HyperText Transfer Protocol Secure) uses SSL/TLS to encrypt the communication, ensuring data confidentiality and integrity.

FTP (File Transfer Protocol):

• Layer: Application Layer (OSI), Application Layer (TCP/IP)
• Function: FTP is used for transferring files between computers over a TCP/IP network.