Remove discarded subdomains (wildcard) from subdomain scanners

in flag

I have a server which I use with my own domain name, with a wildcard DNS record. On the server side, I use the nginxproxy docker image to autogenerate VHosts. This allows me to add new websites/pages/services on the fly with their own subdomain simply by starting a new docker container. I also use the nginxproxy/acme-companion docker image to manage letsencrypt certificates for all of these automatically.

The issue I'm having is that when using the subdomain scanner, it shows old subdomains that have been removed for over a year (they never had their own DNS record, it' s all just VHosts behind the wildcard DNS record).

I would like to know how it can possibly detect that and if there is a way to actually delete the old ones, as they are relatively sensitive because related to work and I would rather not have them linked with my personal domain anymore.

I have actually moved to a new server after these subdomains were removed so the IP is different than it was and I really have no clue what I can do.

djdomi avatar
za flag
what is known to the internet, it stays there forever - said a old guy, a wildcard is still valid for any character even if it was removed
in flag
Yeah but the only record on the DNS zone is for the wildcard, not for the matching strings isn't it? Resolving which of the possible subdomains matching the wildcard are actual valid pages is performed solely on my server, in the nginx vhost config. So what I don't understand is how these are still considered valid websites, when they have never been in the DNS zone, and haven't been used or even accessible for over a year.

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