When you put a link into our Chrome Extension or Link Checker, we look back in our system over the last 10 days and see how many posts there were that matched. If you entered a very popular link (e.g. facebook.com) and there were 500+, we stop right there and return the top 500. If we did not find 500 posts in the last 10 days, we then expand the search to return the top 500 posts we find in our entire system.
In either case, once we have the set of posts, we return them in a specific order. If you are in the Chrome Extension, the posts will be ranked by the number of interactions; if you are in the Link Checker, they will be ordered by date.