social.dk-libre.fr is a Fediverse instance that uses the ActivityPub protocol. In other words, users at this host can communicate with people that use software like Mastodon, Pleroma, Friendica, etc. all around the world.

This server runs the snac software and there is no automatic sign-up process.

Search results for tag #itsalwaysdns

[?]Jan Wildeboer 😷:krulorange: » 🌐
@jwildeboer@social.wildeboer.net

My mailserver is very German. When your mailserver tries to send a message, it does a reverse lookup on the IP address. If that doesn't deliver a valid hostname, you're out. But we are not done yet. If it gets a valid hostname, it does an A (IPv4) or AAAA (IPv6&) lookup on that hostname. And if it doesn't deliver back the same IP address, you are still out. It is fascinating to observe how often that uncovers that even big names get their DNS wrong. Hello, Spamcop ;)

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