Random question type

From MoodleDocs

A random question is not a question type as such, but is a way of inserting a randomly-chosen question from a specified category into a quiz.

This means that different students are likely to get a different selection of questions, and when a quiz allows multiple attempts then each attempt is likely to contain a new selection of questions.

You should always keep in mind that Moodle always adds random questions as worth 1 mark, as described in the forum discussion Quiz Questions Default Marks - Strange Behavior.