As a senior technical support engineer, you will be expected to use and be familiar with many different tools, processes, and procedures. You'll be asked about these during the interview and should be able to describe them in detail. If you're not familiar with a specific tool, you can freely admit this and even ask the interviewer for additional information about the tool and how the organization uses it. You must express your desire to learn new tools and processes if hired by the organization. Hiring managers recognize that candidates may not be familiar with all the tools and processes an organization uses, so this is an appropriate answer to this question.