404s logged in error.log?

I was wondering if someone could confirm that requests resulting in a 404 response are by default logged to error.log at error level "error".

Is that normal, or is there some piece of configuration I am missing that will stop them from being logged to error.log? I figured 404s would be an un-exceptional event that doesn't require error logging, but perhaps I'm simply not handling that situation correctly in my configuration. Worth double-checking.

Thank you!