The Open Systems Interconnection (OSI) reference model was created by the Internet Standards Organization (ISO) and it is a reference model used for communication. Each of the seven different layers has different protocols and responsibilities. The Security+ exam focuses mainly on layers 2, 3, and 7:
Here is a brief summary of each layer:
- Application layer: Applications, such as HTTP for accessing the web or SMTP for accessing email, are launched here. The Web Application Firewall (WAF), whose job it is to protect web-based applications, operates at this layer.
- Presentation layer: The presentation ...