Is it common for MBB interviewers being “not familiar” about the case? I've noticed that some of the case is from the firms' case bank, which means that the interviewer might give a case which is not in his expertise / industry focus, while at the same time he might not have been familiar with the case itself.
If it is the case, when the interviewer does not have a clear understanding about the case and some critical numbers, how should I react when facing this kind of confusion? I feel that the interviewers' input is a critical part, and if they are not familiar with the case, it would cause some confusion and make it harder to solve the case.