As I’ve gotten older I’ve gotten less and less afraid of saying “I don’t know”. To friends, colleagues, and even bosses. It’s okay to acknowledge that you don’t have all the answers.
If you’re expected to have an answer and you don’t yet, the sooner you acknowledge that and seek it, the better. Hiding ignorance isn’t a long term strategy for success. Neither is prevaricating, while afraid of revealing that you don’t know.
You’ll always have gaps in your knowledge. Learning can fill them. Other people can fill them. It’s not a shortcoming – it’s an inevitability.