I do have a domain for that. Lets name it "mydomain".
Naming schema is:
[name].[type].mydomain.com
and one for my services:
[servicename].mydomain.com
Like:
uk.vps.mydomain.com
uk2.vps.mydomain.com
tx.vps.mydomain,com
rapsberrypi.wlan.mydomain.com
thinkpad.wlan.mydomain.com...