Any time I've participated in a technical interview as an interviewer we've had the candidate have full access to a computer and web browser.

I don't expect everyone to have everything memorized or get it right on the first try, but if you don't even know what questions to ask or what resources to confer with, I'm usually concerned if the candidate will be a good fit. The candidate can't be expected to instantly warp to the solution but they need to show they can begin to find the path.