What is the purpose of a frame's header and trailer?

The purpose of a frame's header and trailer lies primarily in synchronization and error control. The header contains essential information such as the source and destination addresses, which aids in directing the data to the correct recipient. It also includes control information that helps ensure that the data is properly sequenced and can be correctly interpreted by the receiving system.

The trailer, on the other hand, often includes error-checking data, such as a Frame Check Sequence (FCS), which allows the receiving system to verify the integrity of the frame after it has been received. This process of error control ensures that any discrepancies arising during transmission can be detected and acted upon, such as by requesting a retransmission of corrupted frames.

While addressing is indeed a critical component of the header, it is not the sole purpose of the header and trailer combined. Data storage and user data compression do not pertain to the function of headers and trailers in network frames. Therefore, the focus on synchronization and error control encapsulates the essential roles these components play in ensuring reliable data transmission.