平成31年度春期 ITパスポート試験問90

This question's explanation and your answers so far.

問90

頻出度★★★

入力画面で数値を入力すべきところに誤って英字を入力したらエラーメッセージが表示され, 再入力を求められた。このような工夫をしておく設計思想を表す用語として, 適切なものはどれか。

出典　平成31年度春期 ITパスポート試験問90

解説

問 90

ア
正解 The correct answer is “ア Fool-proof.” Fool-proof is a design philosophy in which the system is built in advance to anticipate that users may perform wrong operations or make invalid input, so that it does not malfunction and can still process correctly. The stem’s situation—entering alphabetic characters in a field where numeric values should be entered causes an error message and a request to re-enter—is exactly a device that detects invalid input, refuses to accept it, and prompts the user for correct input, making it a typical example of fool-proof.
Incorrectイ
“Fail-soft” is the idea of not shutting the system down completely when a failure occurs, but keeping it running by degrading some of its functions. It is not a design that prevents erroneous input itself, so it does not apply to this question.
Incorrectウ
“Fault tolerance” is a design philosophy that lets the system as a whole keep operating normally even when equipment failures occur, through means such as redundancy. Its main focus is tolerance against hardware failures, and it is not a term for a device that prevents user input mistakes.
Incorrectエ
“Rollback” refers to a recovery operation that restores a database or the like to its correct pre-processing state when an abnormality occurs midway through processing. It is neither the name of a design philosophy nor a mechanism that prevents erroneous input in advance, so it is wrong.

ここがポイント

Fool-proof = a design philosophy that assumes users will misoperate or enter invalid input, refuses to accept invalid input, and thereby prevents malfunction (e.g., rejecting alphabetic input in a numeric field and prompting re-entry).
Fail-soft (degraded operation) and fault tolerance (keeping running through redundancy) are fault-tolerance designs for “after a failure has occurred,” differing in purpose from fool-proof, which prevents misoperation in advance.

用語

解答問90ア