ITPEC IP April 2026 Question 33
On computers on the Internet, a range of application programs such as web and e-mail run, and a communications protocol in the application layer that corresponds to each application program is used. Which of the following is a communications protocol that is in a lower layer than these communications protocols, and is commonly used to implement basic communications functions?
Explanation
TCP/IP — the protocols below the application layer that carry the data for web, e-mail and every other application.
Each application has its own application-layer protocol: HTTP for the web, SMTP and POP for e-mail, FTP for file transfer. They all rely on the same lower layers: TCP (transport layer) delivers the data reliably and in order between the two programs, and IP (Internet layer) addresses the packets and routes them between networks. TCP/IP names this common foundation, and the whole suite, of the Internet.
Answer (d)
Why not others:
- •(a) FTP — an application-layer protocol for transferring files
- •(b) POP — an application-layer protocol for receiving e-mail from a mail server
- •(c) SMTP — an application-layer protocol for sending and relaying e-mail
Key rule: Application protocols (HTTP, SMTP, POP, FTP) define a service; they all run on top of TCP (or UDP) and IP, which move the data.
Networks · AI-written, may contain errors
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