Absolutely this. The primary purpose of the interview is to establish whether or not you are competent enough to do the job. This doesn't necessarily mean having all of the skills out of the box, but whether you are capable of picking them up and have the basis to do so. Best piece of advice I could give is don't lie. If you don't know the answer, say so. But, better to follow up with "...but, this how I think it might work" or "...but, this is how I would go about finding the solution".
One of my purposes in interviews was literally to get the candidate to say they didn't know. We can work with people that know their limits; can't work with a bumbling fool that knows no bounds.
This. It's ok to admit you don't know everything in an interview. Some of my most glowing feedback from interviews came from interviews where I answered questions with a flat out "I don't know"
Also:
You do not have to ace the interview just show promise.
What I mean is, even I've gone through interviews where I didn't know all the answers and they still kept wanting to follow up with me. Don't be too harsh on yourself.