There are two services involved. Domain registration and DNS. Most domain registrars now provide some free DNS service, with basic features. I monitor dozens of domains, and I can tell you that these free DNS services with registrars are most likely to have short DNS outages as well.
ClouDNS is a professional, high-quality DNS service and that does one thing well. As far as I can tell, they don’t do domain registration, so that will always be a separate service. One of the things that ClouDNS does well is making Dynamic DNS easier.