Maybe it depends. If you're hiring a specialist in something and they have to google basics/intermediate stuff, it's a problem (e.g. security, networking, user experience design). I've never worked at Facebook, but graphs are a big deal over there and I hear their programming interviews revolve around graphs a lot. Even if it's not the case, it's an interesting hypothetical because they might need people who are skilled with working on graphs. They might favor candidates who can talk about data sets where graphs are the structure of choice at scale. That said, maybe they need to google a few specifics. Idk. I'm not a graph expert. I would have to Google that :D
If they're more of a generalist, they can usually talk about it even if they don't know specifics and if it takes them 5 seconds to Google it because they know what they're looking for, that may be a sign they do know what they're talking about. Some of these folks are the smartest people I know especially since they can tell you exactly how systems are put together.
I think it really depends on the role and what an employer is looking for in a candidate.
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