Question

how is data encapsulated

Answer 1

Explanation:

Data encapsulation, sometimes referred to as data hiding, is the mechanism whereby the implementation details of a class are kept hidden from the user. The user can only perform a restricted set of operations on the hidden members of the class by executing special functions commonly called methods

Answer 2

Answer:

Encapsulation says that data flows down the protocol hierarchy, headers (and trailers) get appended to it and data moves up the hierarchy headers (and trailers) get stripped off.

Example to illustrate :-

Trivial file transfer protocol (TFTP).

TFTP client transfer 200 bytes of data.

4 Bytes of TFTP header gets added.