Which of the following protocols of the TCP/IP suite is used in the application layer of the OSI model?

Question

Options

• ADCAP
• BOSPF
• CARP
• DTelnet

• A
  8% (2)
• B
  12% (3)
• C
  4% (1)
• D
  77% (20)

Explanation

Telnet is correct because it is a remote terminal protocol that operates at Layer 7 (Application) of the OSI model, allowing users to log into and manage remote systems - exactly where end-user services live in both the OSI and TCP/IP models.

Why the distractors are wrong:

• A (DCAP) - Data Link Switching Client Access Protocol operates at Layer 2 (Data Link), not the application layer.
• B (OSPF) - Open Shortest Path First is a routing protocol operating at Layer 3 (Network); it handles path selection between routers.
• C (ARP) - Address Resolution Protocol maps IP addresses to MAC addresses and functions at the Layer 2/3 boundary - well below the application layer.

Memory tip: Application layer protocols are the ones you directly use - think HTTPS, FTP, SMTP, DNS, and Telnet. If a protocol lets a user or application do something visible (browse, email, remote login), it's Layer 7. Routing and addressing protocols (OSPF, ARP) work invisibly underneath to move data around.

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