I would say that asking clarifying questions is ok, and even necessarily, otherwise you may misunderstand the case objective, the company, or unfamiliar terminology. This may steer you down the wrong direction in the case interview.
Before starting you case solving you can ask 2-3 clarifying questions.
Actually there are 3 main types for clarifying questions:
questions that clarify the objective of the case interview
Here the basic things you have to know about the case objective:
If you don't then go for this type of clarifying question.
2. questions about information that strengthens your understanding of the company
In this chapter the main things you have to know are:
Business model: How does the company make money? Do they sell directly to customers or do they sell through retailers or partners?
Products and services: What products and services does the company sell? What benefits do these products and services provide?
Geographic location: Does the company have one location or are they a national chain? Does the company operate in just one country or do they have an international presence?
3. question about definition of a term you are unfamiliar with
Most consulting interviews do not require you to have specialized knowledge or expertise in an industry. Therefore, if you come across a term that you are unfamiliar with, it is completely acceptable to ask the interviewer for the definition.
So these are three main types of claryfiyng questions. If you asking too many questions, the interviewer will probably reply to you smth like this: we don't know/ we'll see later/ its’ not relevant