"fetcher cannot resolve the address" when using an Azure DNS CNAME record for my custom domain

[andreas_dorfer]

Hi,

the card validator cannot fetch my site: https://www.enterprise-software-development.eu/
I get ERROR: Fetching the page failed because the fetcher cannot resolve the address.
However, the site works fine for all other purposes. The Google crawler has indexed my site with no issues. The Bing crawler has indexed my site with no issues.

I already did some investigation. Here’s my setup:

• The content is hosted on an Azure CDN
• I’m using Azure DNS for my custom domain

When I use the link to the CDN without my custom domain, the card validator works without any problems: https://esdblog.azureedge.net/. So, there must be a problem with the DNS resolution.

I use a CNAME record to map www.enterprise-software-development.eu to the Azure CDN endpoint:

I think the issue is with your resolution of the CNAME record. @farsad_gh is talking about it in another topic https://twittercommunity.com/t/card-image-cant-fetch-by-validator/114895/14

I happen to map the root domain to another Azure CDN endpoint:

There is no issue with the A record. The card validator is able to fetch http://enterprise-software-development.eu/ with no problems (if you check the page in your browser, you have to know that there’s a JavaScript redirect to the www subdomain). (I deliberately used http instead of https because I don’t have a valid certificate for the root domain. However, even if I use https://enterprise-software-development.eu/ for the card validation, the card validator is at least able to fetch the site and responds with “other errors”.)

I hope my info helps to reproduce the issue. I’d really appreciate if you could look into it.

Thank you very much!

[andreas_dorfer]

I just checked the DNS resolution using https://digwebinterface.com/?hostnames=www.enterprise-software-development.eu&type=&ns=resolver&useresolver=8.8.4.4&nameservers=
No problems.

Does your DNS resolver have an issue with the number of steps required to get to the actual IP address?

As I’ve stated initially, the card validation works for https://esdblog.azureedge.net. As you can see in the above image, “esdblog.azureedge.net” is the second step in the resolution of “www.enterprise-software-development.eu”. Is it possible, that the one additional step it takes to resolve “www.enterprise-software-development.eu” is one step too much for your DNS resolver? Do you have a limit on how many CNAME entries you follow?

[andreas_dorfer]

Looks like I’m not the only one having troubles using Twitter Cards and Azure CDN. I’ve found 4 more topics having the same issue:

ERROR: Fetching the page failed because the fetcher cannot resolve the address

Description of issue: The Twitter Bot will not connect to https://jt23.uwbadgers.com or http://jt23.uwbadgers.com. The validator responds with “ERROR: Fetching the page failed because the fetcher cannot resolve the address.”. Attempting to share that address from our dev Twitter account results in the same issue. The site is being served by an Azure Microsoft CDN Endpoint and IPv4 DNS is being provided by RackSpace. Please help! UW Badger Devs URL affected (must be public): https://jt23.uw…

Twitter card image not working with CDN URL

Twitter card not showing up with image from Azure CDN. This used to work and now it doesnt. Something on Twitter’s side changed. This has already been brought up. Reopen this!

Image not rendering on Twitter Card - Card Validator reports no issues

Description of issue: Twitter Cards are not displaying the image.- The Card Validator reports no issue - Even the raw JSON response from the validator does not indicate any issue. here is what the validator displays which echoes the experience when pasting a link into a Tweet. [card_validator] URL affected (must be public): The image link is https://cdn.leasing.com/cms/lead-image.jpg Troubleshooting steps attempted [note that we will not prioritise posts unless there is evidence of fo…

Problem with cards after redirect traffic to https with CDN

In the past, we could see the cards corretly, but after some infraestructure changes in our site we couldn’t. The principal changes was: Change protocol to https Change CDN infraestructure Now, we have a Azure platform with Trafic Manager to redirect request to origin platform. When test the cards in validator, in origin works correctly, but if we try to validate with the correct domain we receive the error: ERROR: Fetching the page failed because the fetcher cannot resolve the address. Af…

[farsad_gh]

@andreas_dorfer I spend several hours on testing and contacting the support team of Azure, NameCheap, and Twitter. As you can see in my topic, I finally found that the issue comes from Twitter’s DNS resolution software.
I put my site and Azure CDN over CloudFlare CDN as a temporary fix.
On the first attempt, when the validator fetching the image it’s not in CloudFlare CDN, So it fails. But for the next times, it could fetch the image, because it cached by CloudFlare CDN.

Hope this helps you until it get fixed.

[andreas_dorfer]

@farsad_gh thank you for your advice! Good to know that I can use CloudFlare as a workaround.

I just found a blog post about the issue. According to the post, the issue only happens with the Microsoft CDN. If you choose Verizon or Akamai, there should be no issue (see https://docs.microsoft.com/en-us/azure/cdn/cdn-features).

[andreas_dorfer]

Hi @andypiper, I’m writing to you directly because I saw that you’ve replied to most of the topics I’ve linked.

I think it’s fair to say that it’s no longer an issue with a single URL or domain. It’s a general issue when using Azure Microsoft CDN and custom domains.

Maybe you can report the issue again.
Thank you very much!

[andreas_dorfer]

Other apps have no issues showing my card. For example, Microsoft Teams:

[andreas_dorfer]

Do you plan to look into it? Would be good to know. Because up until now I haven’t changed anything on my setup so you can reproduce the issue. But if you don’t look into it anyway, I might as well change my setup to work around your DNS resolution issue.

[andreas_dorfer]

You can no longer reproduce the issue. I’ve changed my deployment setup to work around your DNS resolution issues.

For everyone facing the same issue: you can switch to Akamai CDN or Verizon CDN pricing tier.