My employer (a large Tech company with about 10k employees) recently blocked every sports related website along with YouTube, Netflix, and every video and music streaming service possible (Spotify, Pandora, Apple music, etc.), citing bandwidth issues as the reason. There was a vague statement claiming they will review this policy in the future. I can understand blocking Netflix, but blocking music streaming services and sports news websites seems ridiculous for a technology company.
What websites does your employer block? Should an employer block any websites?
It lasted less than a week. When they realized productivity plummeted to the deepest, darkest depths of the metaphorical ocean and the company was better off having happy, productive employees free to do what they want than miserable employees who hardly get any work done.
There's also a generic filter, mostly used to block porn sites. I've noticed it blocks anything with "hack" in the URL which is a problem on occasion ("shack" gets blocked an issue when its part of a client's domain name like "Shackel"). I almost never hit it except on false-positives so it doesn't really bother me any. I think I can at least agree people shouldn't be browsing porn at work.
AFAIK the only logs kept are who hit the generic filter, what they were trying to access, and when. General browsing isn't logged or I'd probably be in more trouble for browsing HN so much.