Match the following : List I (Protocol) List II (Layer) p. SMTP 1. Application…
2024
Match the following :
List I (Protocol) | List II (Layer) |
p. SMTP | 1. Application layer |
q. BGP | 2. Transport layer |
r. TCP | 3. Data link layer |
s. PPP | 4. Network layer |
5. Physical layer |
Answer: B. p-1, q-4, r-2, s-3 — Concept: Protocols are conventionally classified by the OSI/TCP-IP layer whose job they perform, not necessarily by every layer they happen to pass through.…
- A.
p-2, q-1, r-3, s-5
- B.
p-1, q-4, r-2, s-3
- C.
p-1, q-4, r-2, s-5
- D.
p-2, q-4, r-1, s-3
Attempted by 315 students.
Show answer & explanation
Correct answer: B
Concept: Protocols are conventionally classified by the OSI/TCP-IP layer whose job they perform, not necessarily by every layer they happen to pass through. Application-layer protocols implement the actual network service an application relies on — such as mail transfer, web transfer, or file transfer — whether a person or another program invokes it; transport-layer protocols manage end-to-end delivery between two hosts; network-layer protocols handle routing/addressing across multiple networks by function (even when a specific implementation rides over a transport-layer connection); data-link-layer protocols frame and move data across a single link; and the physical layer only concerns raw bit transmission over the medium (voltages, radio signals, optical pulses) with no framing or addressing of its own.
Application to this item — match each protocol to the layer whose job it actually performs:
SMTP (Simple Mail Transfer Protocol) is used directly by mail clients/servers to exchange email messages, so it belongs to the Application layer.
BGP (Border Gateway Protocol) exchanges routing information between routers across autonomous systems on the internet; its role — deciding routes between networks — is a Network-layer function, so it is classified there by convention even though BGP sessions themselves run over a TCP connection.
TCP provides reliable, ordered, end-to-end byte-stream delivery between two hosts — the defining job of the Transport layer.
PPP (Point-to-Point Protocol) frames packets, detects transmission errors, and can authenticate the link (via PAP/CHAP) before data flows across a single point-to-point connection — framing and link management are Data Link layer responsibilities, not the Physical layer's raw-bit-transmission role.
Cross-check: since SMTP, BGP, and TCP each have one unmistakable, well-known layer, the only genuine decision point among the given options is where PPP sits. A framing/authentication protocol is inherently a layer-2 (data link) function — the physical layer has no notion of frames or authentication at all — so p-1, q-4, r-2, s-3 is the consistent, verifiable mapping.