Nameserver

[JxstErg1]

Adding to what @EdwardHamHam said, if you don’t have too much money or a credit card and want free custom domains you can try this, though it’s at the cost of waiting or having some cents on your credit card:

Where do I get free domains?

You can try using EU.org or PP.UA (the latter one if you have a credit card even with a few cents on it and a phone number to use for verification, though the credit card is used only once for verification and then what’s free will remain free) as a valid alternative to Freenom (and Dot TK because Dot TK and Freenom are the same) that also supports Cloudflare and other things that Freenom with its domains supported.

In the case of the first one you’ll get to add the nameservers right at the domain creation step; for the other you’ll have to change them afterwards.