The most common correct answer to “which of the following is an application layer protocol?” is HTTP (HyperText Transfer Protocol).

Quick Scoop: What Is an Application Layer Protocol?

An application layer protocol is a network protocol that operates at the top (Layer 7) of the OSI model and directly supports user applications like web browsers, email clients, and file-transfer tools. It defines how application data is formatted, sent, and interpreted between devices so that different programs can communicate reliably over a network.

Common examples include:

  • HTTP – web browsing.
  • HTTPS – secure web browsing over TLS/SSL.
  • FTP – file transfer between client and server.
  • SMTP – sending email.
  • DNS – translating domain names (like example.com) to IP addresses.
  • Telnet / SSH – remote login to another machine.

How To Recognize the Right Option in MCQs

When you see a multiple-choice question like “which of the following is an application layer protocol?”, look for protocols that you know are used directly by applications , not by the underlying transport or network mechanisms.

  • Typically application layer in options:
    • HTTP, HTTPS, FTP, SMTP, POP3, IMAP, DNS, DHCP, Telnet, SSH, SNMP.
  • Typically not application layer:
    • TCP, UDP (transport layer).
* IP, ICMP, ARP (network / related layers).

So if the choices included something like:

  • TCP
  • IP
  • HTTP
  • ICMP

Then HTTP is the application layer protocol.

TL;DR: In most exam-style questions, the correct pick for “which of the following is an application layer protocol?” is HTTP , and more generally, any protocol used directly by user-facing applications (HTTP, FTP, SMTP, DNS, etc.).

Information gathered from public forums or data available on the internet and portrayed here.