Thanks, I couldn't read the article.
They are for me, apparently because I'm using cloudflare's DNS service, and cloudflare is returning its own IP when I query for archive.vn's.
$ dig +short @8.8.8.8 archive.vn
5.196.68.232
$ dig +short @1.1.1.1 archive.vn
1.0.0.1
1.1.1.1
They don't return themselves for all hosts, $ dig +short @1.1.1.1 google.com
172.217.9.14
I wonder by what criteria they intercept, and if this by archive.vn's or cloudflare's initiative.