Based on the latest update from from DynDNS this issue has been resolved.

The DNS resolution mitigations Heroku has made seem to have corrected the issue. We'll continue monitoring.

We have confirmed an outage with our DNS provider, DynDNS. The issue is intermittently affecting DNS resolution for codetree.com. The issue is being worked on by both DynDNS and Heroku. You can track status here https://status.heroku.com/incidents/965 and here https://www.dynstatus.com/incidents/nlr4yrr162t8.