I went as a fresher for te interview. We initially had a written test, which tested all basic skills, personality and IQ . We had to wait hours in a big university to go through the test. The results of this test was posted on Company's website. I did go through the second round, which was a technical interview. Whether you know the answer or not,was not important. But the confidence exhibited during the process was important. The employeer needed challenging people who can quickly learn new things. Project this to the recruiter.Don't worry if you dont know the answer,but face the interview with confidence,ensuring that you can learn any new skill.