There is a website which is distributed via Azure CDN. The CDN endpoint was used as a destination of CNAME entry for
www.< EXAMPLE >.com with usage of Google DNS. The www address to the website works fine with one exception, twitter cannot resolve the address
https://www.<EXAMPLE>.io, thereby it cannot read meta tags to generate so called twitter card. On the twitter validator page when you try validate above address it will return following message:
ERROR: Fetching the page failed because the fetcher cannot resolve the address.
However, when you enter CDN endpoint address (
https://EXAMPLE.azureedge.net) in the same validator then everything is fine and Twitter is able to read the website content. Also facebook sharing debugger doesn't complain.
Below you can see obscure
dig output for
www.EXAMPLE.io. 60 IN CNAME EXAMPLE.azureedge.net. EXAMPLE.azureedge.net. 1799 IN CNAME EXAMPLE.afd.azureedge.net. EXAMPLE.afd.azureedge.net. 299 IN CNAME afd.t-XXXX.t-msedge.net. afd.t-XXXX.t-msedge.net. 200 IN CNAME t-XXXX.t-msedge.net. t-XXXX.t-msedge.net. 43 IN CNAME XXXXXXXXXXXXX.ctrl.t-XXXX.t-msedge.net. XXXXXXXXXXXXX.ctrl.t-XXXX.t-msedge.net. 223 IN CNAME standard.t-XXXX.t-msedge.net. standard.t-XXXX.t-msedge.net. 236 IN A 188.8.131.52
What can cause the problem and how can I fix it?