Is there some mechanism for remotely determining what virtual hosts are configured on a server?
For example, I have a domain, say example.com, and I'm running an Apache server.
Let me then create a virtual host, say virtual.example.com on that server in the standard manner, perhaps running Flask on localhost, again, in the standard manner.
Since I have only the domain example.com registered, any subdomain resolves to the IP address assigned to example.com, so https://virtual.example.com will resolve to my IP address, Apache will do its magic, and the request does the right thing.
These subdomains are generally used for testing purpose only and I set up and tear down these virtual hosts on a regular basis. The subdomains are not registered, since they don't need to be. They are not advertised in any way of which I'm aware.
However, I see attempts by remote IPs, mostly the Usual Suspects like Expanse and ZoomInfo, attempting to connect to these virtual hosts in my logs almost immediately, which leads me to believe that Apache provides some mechanism for a curious remote user to query this information from my server.
Bear in mind everything is working correctly and that I'm not especially worried about probes, etc.
I've scoured the Apache documentation and searched the web for an answer and thus far come up empty handed.
I hope I'm phrasing this coherently and that I'm asking in the right forum (if not, please direct me to the right one).
