[time-less-ness]

I would fail your interview. I assume interviews are for what I do/don't know. So I honestly say what I don't know, and would not offer to find out. Not right then anyway.

Unless you make it very clear at the outset of the interview that this is exploratory and we will be working with network connectivity and full access to the world's knowledge.

I have sent followups to interviewers on problems that were interesting or deep, but those conversations never turned into anything.

[globular-toast]

I don't think the commenter meant to literally look stuff up during an interview. A good interview is more of a conversation than an exam. During that conversation it would be perfectly normal, even expected, for the interviewee (or even interviewer!) to say something like "I would need to check the specifics in the documentation" or "I don't know what X is, but let's assume it's Y".

Nobody can possibly hold all the knowledge they'll need in their head at once. A fundamentally important part of any skilled job is being able to adapt, improvise and learn on the job. This is what is being tested, not what you know/don't know.

[api]

I'm not looking for someone who can autodidact something on a whiteboard during an interview. That'd be kind of silly unless it's something very small. It's more of an attitude, a desire and willingness and ability to learn stuff you don't know yet or try new things.