hi there.. i just sign up for member and payment successes, but i cannot found dynu.com, dynu.net domain as you said on popup... can you explain me

i asked dynu yesterday because im a new member as well this is what i asked

Description: im confused by which domain name should i use does it matter or
should i just use the default one it is on which is ddnsfree.com

they replied to me saying this:
"You can use any domain name, they are all the same when it comes to
functionality. Yes, you can go with ddnsfree.com or the default one

ok and so now if your a member i figured out you get access to dynuddns.com and dynuddns.net, aswell as some other servers, they changed the name a while back from dynu to dynuddns, and made their server members only that's why it can get confusing, but like they mentioned.. if the free servers have all the same functionality id imagine all the member servers have the same functionality compared to each other as well