In OSI, data encapsulation starts from which layer?

Data encapsulation is the process of adding extra information to data as it moves through the layers of a network model. Each layer adds its own header (and sometimes trailer) to help with delivery, routing, and other network tasks.

This process starts at the Application Layer in the OSI model. At this layer, the user’s data is created, such as an email or a web page request. As this data moves down through the layers (from Application to Presentation, Session, and so on), each layer adds its own control information.

By the time the data reaches the Physical Layer, it is fully encapsulated and ready to be sent as bits over cables or wireless signals.

Key points about data encapsulation:

• It starts at the Application Layer


• Each OSI layer adds its own header (and sometimes trailer)


• It helps with proper data delivery between sender and receiver


• It ensures that each layer’s tasks are carried out smoothly

Encapsulation is important because it allows different network functions to work together in a structured and organized way. It also helps in troubleshooting by identifying where an issue may have occurred in the transmission process.