I got hit by this too.
In case it's helpful to anyone else, I found that I could still log in to my no-ip account and get the current IP address from there.
If you do a cname redirect from a "real" domain to a no-ip dynamic domain, like I do, you can probably do some DNS magic on the real one to get things back up and limping. It won't survive address changes but it's better than nothing.
I am not sure if no-ip's service is still registering address updates even though it can't resolve them.
Biting the hand that feeds IT
