When I run the fCC tests against your project, I get this error
frame-runner.js:98 TypeError: Cannot read property 'toLowerCase' of undefined
at eval
in the browser console, which means the tests are getting an empty response. That’s probably because you’re sending a status of 400, which the tests interpret as failure. So you would need to remove that despite it making sense for a real app.
I can’t get glitch to fork and run right now, but you should log all your inputs and responses to your isValidUrl function in your URL controller because I believe it has the same problems I discussed here. The fCC tests don’t send a bare URL; they have some URL parameters tacked on as well that dns.lookup() cowardly refuses to handle.