Which of the following protocols operates at the Application Layer?

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Accepted Answer

FTP - FTP (File Transfer Protocol) is a protocol that operates at the Application Layer of the OSI model, which is the seventh and topmost layer.

The main purpose of FTP is to allow users to upload and download files over a network. It is used when a user wants to send large files from one computer to another or retrieve data stored on a remote server.

Key features of FTP:

  Allows file sharing between different systems.
  Supports user authentication (username and password).
  Can work in active or passive mode depending on firewall and NAT settings.
  Uses separate connections for control and data (usually port 21 for control).


At the Application Layer, FTP provides a user interface that communicates with lower layers to transmit the data. It does not concern itself with how the data is routed or delivered. Instead, it focuses on what the user wants to do—send, receive, rename, delete, or list files.

Other common Application Layer protocols:

  HTTP/HTTPS – for web browsing
  SMTP – for sending emails
  DNS – for resolving domain names


Conclusion: The correct answer is FTP. It operates at the Application Layer and is designed to handle file transfers between systems across a network. This protocol is essential for tasks like website management, file backup, and server administration.

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