What levels of the OSI model do you know?

1. Physical Layer - Transmission of data bits over the physical medium. Defines electrical, mechanical, and procedural parameters of the communication channel.
2. Data Link Layer - Ensures reliable data transfer between nodes within the same network segment. Responsible for addressing within the local network (MAC addresses), error detection, and correction.
3. Network Layer - Responsible for routing data between different networks. Defines logical addressing (IP addressing) and the selection of the optimal path for packet delivery.
4. Transport Layer - Guarantees data delivery between application processes on hosts. Provides mechanisms for segmentation, ordering, and flow control. Protocols: TCP, UDP.
5. Session Layer - Establishes, manages, and terminates communication sessions between applications. Responsible for dialogue synchronization and data exchange management.
6. Presentation Layer - Transforms data to be understandable by the application. Performs format conversion, compression, and encryption functions.
7. Application Layer - Provides network services for user applications. Examples of protocols include HTTP, FTP, SMTP, DNS.

# Example of layer interaction (simplified)
# Data from application (layer 7)
# Presentation layer headers are added (layer 6)
# Session layer headers are added (layer 5)
# Transport layer headers are added (TCP/UDP, layer 4)
# Network layer headers are added (IP, layer 3)
# Data link layer headers and trailer are added (MAC, layer 2)
# Data is converted into bits and transmitted over the physical channel (layer 1)

# Upon receiving data, the process occurs in reverse order,
# processing headers at each layer.