That depends on the intentions of the person. ARMOR K9 protection dogs are trained to alert (bark) when something is seen as unfamiliar, out of place, or a threat. However, if the intentions are to harm you, then your dog will likely switch into protection dog mode but should not bite unless commanded to do so.
The intent is the key here. If your best friend stops by with intentions to harm you, your dog will provide protection when commanded despite having had many interactions with this person. But if he stops by to say hi and borrow your favorite tool, your dog will enthusiastically greet him and probably look for some belly rubs!