In general URLs should be in the form of
example2.com, etc. Using the real URL is not necessary so it really should be generic in the question.
If the visiting the URL is required to answer the question it should just be closed as changing the URL completely makes the question useless. Questions that require us visiting the site are not a good fit for this site as those links may die and the question is probably too specific to that site to be useful to others anyway. Basically, if you can't explain your problem without us visiting your site it is probably not a good fit for the Q&A portion of this site. But it would be great in chat.
Like everything else, there may be times where a URL is not changed. We may be so wrapped up in answering the question we forget other details. Or we may determine that in that particular case that this is something that would be worth leaving as it because for some reason it adds value to the question (I'll leave that ambiguous). But there is no actual set "rules" as to when this might happen.
But, in general, we should be removing links to an external site and using