Which of the following network access standards is used to connect a station…
2011
Which of the following network access standards is used to connect a station to a packet-switched network?
Answer: C. X.25 — ConceptA network access recommendation identifies the boundary and service it standardizes: user equipment to network, packet assembly/disassembly, a general…
- A.
X.3
- B.
X.21
- C.
X.25
- D.
X.75
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Show answer & explanation
Correct answer: C
Concept
A network access recommendation identifies the boundary and service it standardizes: user equipment to network, packet assembly/disassembly, a general DTE-DCE interface, or inter-network signalling.
For packet-mode access, the defining scope is the DTE-DCE interface that carries packets between a terminal and a public data network.
Application
The stem asks for the standard used to connect a station to a packet-switched network. X.25 defines the interface between DTE and DCE for terminals operating in packet mode on public data networks.
Contrast
X.3 specifies a Packet Assembly/Disassembly facility (PAD) in a public data network.
X.21 specifies the DTE-DCE interface for synchronous operation on public data networks.
X.25 specifies packet-mode DTE-DCE access to public data networks.
X.75 specifies packet-switched signalling between public networks.
Cross-check
The boundary test confirms the result: station-to-network packet-mode access selects X.25, whereas network-to-network signalling would select X.75.
Result
Therefore, the required standard is X.25.