Reddit knows who I am before I log in

Reddit probably tracks IPs of each visitor, I’m sure, but I cannot possibly be the only person in a k-12 school browsing reddit. The school has one public IP address.

So why do I so often see a link on the generic front page – before I log in – from a subreddit I’m subscribed to, usually at the top or within the top 3 links of the front page? They aren’t upvoted so much to the point where they would be there naturally. They are often in not-unknown subreddits, but subs that definitely aren’t part of /r/popular or probably within the top 10% of subreddits by traffic, I’d hazard.

I get that the logged-out front page shows me top links for my geographic information, that much is clear. But does it know what subreddits I’m subscribed to before I log in even? Or is this just curious coincidence? It happens nearly every time I open my browser, before logging in, so if it’s showing me a combined front page with all visitors from this school’s network, maybe I’m only recognizing the one subreddit I’ve contributed to the whole umbrella identity it has formed for this IP address, but that’s doubtful too, as it’s usually the top link.

Chrome (up-to-date), Win 7 (up-to-date), RES installed.

I suspect it probably has to do with RES, which likely does a background login or at least a background /u/ lookup, since it shows me my current karma points before I log in as well. But if someone can confirm, that would be great!

Found here /// Privacy Galaxy!