Is that because it's behind cloudflare? I'm pretty sure it still runs primarily on a single server in a Colo (i.e. except in times of hardware failure or other physical realities).
It's also possible to get a copy of HN from Cloudflare in addition to M5. I keep historical DNS data and can confirm there are Cloudlfare IPs that continue to work.
whois is returning AWS and I don't see any of the normal cloudfront headers, but I do see a server header of nginx. So it doesn't look like cloudflare to me, I'd guess they're just running some ec2 instances with nginx configured to give the exact behaviour they need (as I recall they return cached pages to non logged in users, which is why you can sometimes log out and get the page to load when they're having issues). I also see awsdns in their ns records, so it looks to be like they're just doing Geo-dns in route53 to route to the closest instance they're running.
