Question: Which of the following is the first layer of the OSI (Open Systems Interconnection) model?
A Physical Layer
B Data Link Layer
C Network Layer
D Transport Layer
Answer: Physical Layer
| Layer Number | Layer Name | Description |
| 7 | Application Layer | Provides interfaces for communication between applications and network services. It deals with high-level protocols such as HTTP, SMTP, and FTP. |
| 6 | Presentation Layer | Responsible for data translation, encryption, and compression. It ensures that data is presented in a format that the application can understand. |
| 5 | Session Layer | Manages sessions and dialog control between two devices. It establishes, maintains, and terminates connections. |
| 4 | Transport Layer | Manages end-to-end communication, ensuring data reliability and integrity. It includes protocols like TCP and UDP. |
| 3 | Network Layer | Handles routing, addressing, and logical topology of the network. It is responsible for packet forwarding. |
| 2 | Data Link Layer | Manages data framing, error detection, and flow control on a link. It is divided into sublayers like LLC and MAC. |
| 1 | Physical Layer | Manages the physical medium, including electrical, mechanical, and functional aspects. It deals with bits and signals over the network medium. |