You will likely be asked about a topic you are not familiar with during an interview. Even though docker containers are commonly used in information technology infrastructures, you may not have come across them in your career. If that is the case for this question or any other topic, the best strategy is to admit that you have not used the technology or are unfamiliar with it. Then describe to the interviewer how you would locate the information or learn about the topic. This will help you establish your credibility with the interviewer and demonstrate your willingness to learn new technologies.