Questions are encouraged. If you don’t ask, you’ll never know. But go in with as much knowledge as possible.
There are no dumb questions but there are lazy questions. Especially in an environment where you may be being evaluated for your knowledge level, it’s important to go in with as much information about the subject you’re asking about. Asking a question is a transaction. You get an answer, the other person gets the gratification of solving your problem for you.
Once you’ve exhausted all your resources, you then can ask the question. Don’t ask without checking several places. Make the transaction worth the while for the person you are asking.
The majority of the questions you ask, if haven’t used this level of checks and balances before, can be answered yourself by searching.