Free .IPQ.CO Subdomain
|Notes||Once assigned, you can't change the IP, nor remove the entry.|
IPQ.CO allows mapping a subdomain to an IP, so it's a dynamic DNS in a way, but with one caveat: you can only set the IP address once.
In this sense, it allows setting an A record, but if you do, be absolutely positive that you don't ever need to change it. This limitation makes it highly unusable for websites. It also means hundreds of good domain name prefixes are likely already used out.