In data communications, which method historically allows a user to connect to a remote computer over the public switched telephone network using a modem?

Introduction / Context:
Before ubiquitous broadband and always-on networking, remote computer access commonly relied on analog telephone lines and modems. Knowing the term for this connection method is part of basic networking history and terminology.

Given Data / Assumptions:

• Goal: connect to a remote computer.
• Medium: public switched telephone network (PSTN) via modem.
• We seek the recognized name for this method.

Concept / Approach:
Dialup networking uses a modem to modulate digital data onto analog phone lines and demodulate at the other end. The connection is established by dialing a phone number, often authenticated by terminal servers or ISP access servers, providing terminal sessions or IP connectivity (PPP/SLIP).

Step-by-Step Solution:
Identify legacy remote access scenario using phone lines.Recognize that a dialed telephone call is the key characteristic.Select the term ‘‘Dialup’’ for such connections.

Verification / Alternative check:
Historical ISPs provided dialup numbers; operating systems shipped with dialup networking clients. The term was standard across documentation and user guides.

Why Other Options Are Wrong:

• Device: A generic noun, not a connection method.
• Diagnostic: Refers to testing/troubleshooting, not connectivity.
• Logic circuit: Digital hardware concept, not networking method.
• None of the above: Incorrect because dialup is exactly the right term.

Common Pitfalls:
Confusing dialup with leased lines or broadband. Dialup is on-demand, telephone-number-based, with limited bandwidth (e.g., 56 kbps maximum under ideal conditions).

Final Answer:
Dialup