How can I use an empty domain name?

Question

Domain name market

It so happened that they left me a domain name (the owner refused, gave all his details and said, "do whatever you want with it"), which I pay for because the sites that I created for my friends work on subdomains. Changing subdomains to something else will be extremely painful for everyone. Someone has their own page, someone has a small business card site.
On the Internet, except for old articles about cybersquatting and parking for 2008-2012, I did not find anything.
Advise how you can use this domain name (4 digits, not quite sure if you can mention the real name here (so no secret)), what to do, maybe even manage to pay for it - that would be ideal.

Answer 1

own DNS server.