問36
頻出度★★★
合意したサービス提供時間帯のうち, 実際に顧客が IT サービスを利用できた時間の割合で表されるものはどれか。
令和7年度 ITパスポート試験 問36
マネジメント系サービスマネジメント › サービスマネジメントシステム
This question's explanation and your answers so far.
解説
問 36
- ア
正解 The correct answer is ア (Availability). Availability is a metric expressing the proportion of time during which an IT service was actually usable, out of the agreed service delivery time period. As a formula it is “Availability = actual usable time ÷ agreed service delivery time”. For example, if the agreed delivery time is 100 hours and the service was unavailable for 1 hour due to a failure, the availability is 99 ÷ 100 = 99%. The statement in the question, “the proportion of time during which the customer could actually use the IT service, out of the agreed service delivery time period”, is exactly the definition of availability. In service management (service availability management), this availability is continuously monitored and maintained in order to meet the service level agreed in the SLA. Therefore, the correct answer is ア.
Incorrectイ
Functionality is a quality characteristic concerning whether a product or service has the required functions and operates correctly. It is not a time-based metric like “the proportion of usable time”, so it is incorrect.
Incorrectウ
Efficiency is a metric expressing how much output is obtained relative to the resources invested (time, cost, personnel, etc.); in software quality it refers to processing performance or low resource consumption. It is a different concept from “the proportion of time the service was usable”, so it is incorrect.
Incorrectエ
Usability is a quality characteristic concerning how easily and comfortably users can use a product or service. It expresses ease of operation, not the proportion of usable time (i.e., availability), so it is incorrect.
ここがポイント
- Availability = actual usable time ÷ agreed service delivery time. It is a central metric in service management (service availability management) and serves as the basis for measuring how well the SLA is met.
- Functionality, efficiency, and usability are all quality characteristics of software/services, but it is important to distinguish that the only metric expressed as a “proportion of time” is availability.
用語