companies are getting smarter these days with interviews. they don't ask things they know you could have picked off the internet and memorized. If you are a fresh gradute, then I agree that its 90% your personality and grades. I myself give good review to fresh grads if I like their personality and even if they don't answer any of my questions. My suggestion is not to give up and become frustrated during the interview.
For experienced people, if they put it on their resume, I expect them to know it. Before the interview, I study their resume and ask questions directly from it. even if I don't understand their response completely during the interview, I write down their solution in the interview and simulate it after the fact and before giving my feedback to the company. Worst thing in my eye is if you put it on your resume then struggle with it during the interview. For experience people is 75% knowledge and the rest personality and ability not to get frustrated during the interview.