Most network engineers are familiar with standard networking technologies, practices, and procedures. However, only the more advanced senior networking engineers will know of unique techniques used to improve the performance or efficiency of a network. Using a secondary router falls into this latter category. As the interview progresses, you will be asked more challenging questions. This indicates that the interviewer is gaining confidence in your capabilities and is willing to explore your background more. Continue to answer these technical questions directly and to the point. As always, the interviewer will ask a follow-up question if they need additional information.