macPorts: only distfiles has public repo, no timestamp, too large to loop through
NetBSD: http://ftp.netbsd.org/pub/NetBSD/ has public repo, no timestamp, web directory hard to loop through, no mirror tracker
opensuse: http://download.opensuse.org/ has public repo, a possible timestamp called latest in history, our mirror doesn't have this file tho, no mirror tracker
scientific: https://scientificlinux.org/downloads/sl-mirrors/ (CSC not listed)
trisquel: https://trisquel.info/mirmon/index.html out of date website
pkgsrc
qtproject: https://download.qt.io/
raspbian: http://archive.raspbian.org/raspbian/ snapshotindex.txt is most likely a timestamp, tho i'm not sure. also i think our mirror is completely outdated, it's not listed on official mirror list
slackware: https://mirrors.slackware.com/mirrorlist/ https://mirrors.slackware.com/slackware/ checking using the last updated date here, don't know if it's entirely accurate
trisquel: https://trisquel.info/mirmon/index.html out of date website!? please recheck this!!!
ubuntu-ports: http://ports.ubuntu.com/ubuntu-ports/ checks the file anonster.canonical.com, which appears to be a timestamp (check it to make sure!!!)