Why do you think so? And, I'm hopping you don't rely on timing on this level.

An experienced sysadmin would have little experience with basic tasks, since he solves them around once or twice per job. And you never know the environments they tried it before, that may be completely different from what you are presenting them right now.

I'd say "installing X" is a test for encyclopedic knowledge, and a very unreliable test for expertize. That's the kind of test that gave bad names to IT certification at the early 2000's.