Which OSI model layer is responsible for reformatting, compressing, and encrypting data so the receiving application can read it?

• A. Application Layer (Layer 7)
• B. Presentation Layer (Layer 6)
• C. Session Layer (Layer 5)
• D. Transport Layer (Layer 4)

Answer: (B)

Reformatting, compressing, and encrypting data so the receiving application can read it are handled by the Presentation Layer. This layer sits between the Application layer and the lower layers and manages how data is represented and transformed for the application: encoding formats, syntax translation, data compression, and encryption. When data is sent, the Presentation Layer formats it into a common representation; on the receiving end, it decompresses, decrypts, and decodes the data so the Application layer can use it correctly. The other layers don’t manage those representation tasks—the Transport layer focuses on reliable delivery, the Session layer on dialogue control, and the Application layer on providing services to applications.