Well,it depends what you're doing at the time.If you're installing something you think is legit,it'd be most likely normal to expect a change.If you feel that change is legit,then you'd Allow it.If something appears out of nowhere,that might not be a good thing(though not always,some things autoupdate,etc.)
Look at that,two advisors for the price of one,lol.Stop sneaking up on me,Bitman,lol.