There are a few primary or top-level questions the interviewers are keen to know the answers. Many questions are formulated around these top-level questions in order to find out more about you. The primary interests of the interviewers are:
1. Are you the best candidate to hire?
Comparing with all the other applicants, are you the 1st choice? Explain to me why you are the 1st choice.
2. Can you handle the job?
Consider if you have the right attitude, qualifications, specific skills and experience to do the job.
3. Can you fit into the current organization?
Are you a motivated person who is able to blend in with the group? Human interaction is important especially for organization with very less employees.
4. If I offer you this job, will you take it?
Are you keen for this opening? How much do I need to offer you for this job?
5. Do I make the right decision to hire you?
What if I make a mistake? Do I make myself a no-brainer? Obviously the interviewer does not want to find out later that you are not the right person to hire. It may jeopardize his or her credibility with the company.