Can you discuss what branch testing and boundary testing are and how these apply to the quality assurance process?

This is an example of a follow-up question. Follow-up questions have two purposes. One is to explore a topic in more detail when you have already provided the interviewer an answer to their question. These usually occur immediately after you've answered the interviewer's question about the same topic. Another is to determine if you're consistent with your answers throughout the interview. In this case, the follow-up question will be asked much later in the interview. You should always be prepared for follow-up questions during an interview.