We have made available part of the new container scans feature that sends help emails (if you have help email type turned on, otherwise we send you nothing). The scans we run are every 24 hours and they include basic checks, below is a list of the checks and alerts we send currently, if you have more checks you want done comment on this post.
Unable to PING domain and no NS can be found
This is a great way to find out if you have containers that cant be reached or domains that are gone. If we cant PING your site and the domain NS lookup fails we will send you an alert with the subject
We are unable to connect to your site.
Can PING domain but the NS/A records don't match our server
We will do a PING and NS check on the containers domain, if we cant see our server IP in the A record or we are not the NS of the domain when this is done we will send you an email with the subject
Your domain is not pointing to us. If the NS we get back matches against
ns.cloudflare.com we will assume it's correct and behind the CloudFlare proxy. If we get this wrong you can set a TXT record in your DNS that will allow our checks to pass on this type, you can find more here.