How to configure custom domains on azure web app service and add those in GCP Cloud DNS

Question

How to configure custom domains on azure web app service and add those in GCP Cloud DNS

Rohan 0

We are looking to route traffic from application gateway in azure or without that to a azure web service we have deployed our application to.

We need to however configure the subdomain entries under a purchased domain on Google cloud dns service. As we have already set up a custom domain and added the CNAME and TXT records in GCP DNS , we are not able to access the application with the subdomain url.

Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-03-16T17:03:20.5033333+00:00
HI @Rohan

Thanks for reaching us regarding your issue

To help us quickly identify where the configuration might be failing (DNS, App Service, SSL, or Application Gateway), could you please help confirm the details below?

What is the exact subdomain you are trying to access (for example, app.example.com) could you please share domain name in private message , and does it resolve correctly via a public DNS lookup?

In GCP Cloud DNS, what record is configured for this subdomain (CNAME or A record), and what is the exact target value?

Has this custom domain been successfully added and validated in Azure App Service under Custom domains (no pending validation)?

Are you accessing the application over HTTPS, and is an SSL certificate already bound to this hostname in App Service?

Does the application load correctly when accessed using the default Azure URL (for example, <appname>.azurewebsites.net)?

Is traffic routed directly to Azure App Service, or through Azure Application Gateway? If via Application Gateway, is DNS pointing to the gateway’s public IP and is the same hostname configured there?

Once we have this information, we can provide precise next steps to resolve the issue.
Alex Burlachenko 20,005 Reputation points MVP Volunteer Moderator

2026-03-17T10:14:42.6633333+00:00

Rohan hi and thx for join us at Q&A,

to make a custom subdomain work with Azure App Service the key thing is that two sides must match DNS in GCP and domain binding in Azure. In Azure App Service u must add the exact custom hostname under Custom domains. When u add it Azure will give you a TXT record for verification and usually expects a CNAME pointing to urapp.azurewebsites.net.

In Google Cloud DNS u must create A TXT record for domain ownership verification with the exact name and value Azure provides. A CNAME record for the subdomain pointing to urapp.azurewebsites.net, not to a public IP. After DNS propagates go back to Azure and complete validation so the domain shows as validated and bound to the app.

If u are putting Application Gateway in front then DNS should point to the Application Gateway public IP (A record) and App Service should be configured with the same hostname and a proper SSL certificate. If App Service is accessed internally by the gateway and not directly via azurewebsites.net.

So why its not work, lets think, I assume DNS not fully propagated or CNAME pointing to wrong target or domain not added inside App Service, may be SSL not configured so HTTPS fails. Application Gateway backend hostname mismatch.

Use nslookup or dig to confirm the subdomain resolves exactly to what u expect. If it does not resolve correctly the issue is DNS. If it resolves but shows 404, the hostname is not properly bound in App Service.

Hope it would help.

rgds,

Alex
Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-03-18T16:03:19.1333333+00:00

HI @Rohan

We have reached out to you in Private messages for additional details, could you please look into it and share us the details? Thanks
Shree Hima Bindu Maganti 7,035 Reputation points Microsoft External Staff Moderator

2026-04-02T14:33:36.2633333+00:00

HI @Rohan
If your custom domain is already showing as validated (green tick) in Azure App Service, then no additional setup like Azure Application Gateway is required, and the subdomain should directly load your application. Since it is not loading, the issue is typically related to DNS resolution, SSL binding, or hostname configuration. Please ensure that in Google Cloud DNS the CNAME record for your subdomain correctly points to <appname>.azurewebsites.net and that it resolves properly using tools like nslookup or dig. Also verify that the exact hostname is added and fully bound under Custom Domains in App Service. If the domain resolves but does not load over HTTPS, check that a valid SSL certificate is configured and bound under TLS/SSL settings, as missing SSL can cause the site not to load in browsers. Additionally, confirm that the application is accessible via the default App Service URL (https://<appname>.azurewebsites.net) to rule out any application-level issues. For detailed guidance, you can refer to Microsoft documentation on custom domains.
https://learn.microsoft.com/en-us/azure/app-service/app-service-web-tutorial-custom-domain?tabs=root%2Cazurecli
https://learn.microsoft.com/en-us/azure/app-service/configure-ssl-bindings

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Your answer

Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-03-16T17:03:20.5033333+00:00

HI @Rohan

Thanks for reaching us regarding your issue

To help us quickly identify where the configuration might be failing (DNS, App Service, SSL, or Application Gateway), could you please help confirm the details below?

What is the exact subdomain you are trying to access (for example, app.example.com) could you please share domain name in private message , and does it resolve correctly via a public DNS lookup?

In GCP Cloud DNS, what record is configured for this subdomain (CNAME or A record), and what is the exact target value?

Has this custom domain been successfully added and validated in Azure App Service under Custom domains (no pending validation)?

Are you accessing the application over HTTPS, and is an SSL certificate already bound to this hostname in App Service?

Does the application load correctly when accessed using the default Azure URL (for example, <appname>.azurewebsites.net)?

Is traffic routed directly to Azure App Service, or through Azure Application Gateway? If via Application Gateway, is DNS pointing to the gateway’s public IP and is the same hostname configured there?

Once we have this information, we can provide precise next steps to resolve the issue.
Alex Burlachenko 20,005 Reputation points MVP Volunteer Moderator

2026-03-17T10:14:42.6633333+00:00

Rohan hi and thx for join us at Q&A,

to make a custom subdomain work with Azure App Service the key thing is that two sides must match DNS in GCP and domain binding in Azure. In Azure App Service u must add the exact custom hostname under Custom domains. When u add it Azure will give you a TXT record for verification and usually expects a CNAME pointing to urapp.azurewebsites.net.

In Google Cloud DNS u must create A TXT record for domain ownership verification with the exact name and value Azure provides. A CNAME record for the subdomain pointing to urapp.azurewebsites.net, not to a public IP. After DNS propagates go back to Azure and complete validation so the domain shows as validated and bound to the app.

If u are putting Application Gateway in front then DNS should point to the Application Gateway public IP (A record) and App Service should be configured with the same hostname and a proper SSL certificate. If App Service is accessed internally by the gateway and not directly via azurewebsites.net.

So why its not work, lets think, I assume DNS not fully propagated or CNAME pointing to wrong target or domain not added inside App Service, may be SSL not configured so HTTPS fails. Application Gateway backend hostname mismatch.

Use nslookup or dig to confirm the subdomain resolves exactly to what u expect. If it does not resolve correctly the issue is DNS. If it resolves but shows 404, the hostname is not properly bound in App Service.

Hope it would help.

rgds,

Alex
Praneeth Maddali 7,315 Reputation points Microsoft External Staff Moderator

2026-03-18T16:03:19.1333333+00:00

HI @Rohan

We have reached out to you in Private messages for additional details, could you please look into it and share us the details? Thanks
Shree Hima Bindu Maganti 7,035 Reputation points Microsoft External Staff Moderator

2026-04-02T14:33:36.2633333+00:00

HI @Rohan
If your custom domain is already showing as validated (green tick) in Azure App Service, then no additional setup like Azure Application Gateway is required, and the subdomain should directly load your application. Since it is not loading, the issue is typically related to DNS resolution, SSL binding, or hostname configuration. Please ensure that in Google Cloud DNS the CNAME record for your subdomain correctly points to <appname>.azurewebsites.net and that it resolves properly using tools like nslookup or dig. Also verify that the exact hostname is added and fully bound under Custom Domains in App Service. If the domain resolves but does not load over HTTPS, check that a valid SSL certificate is configured and bound under TLS/SSL settings, as missing SSL can cause the site not to load in browsers. Additionally, confirm that the application is accessible via the default App Service URL (https://<appname>.azurewebsites.net) to rule out any application-level issues. For detailed guidance, you can refer to Microsoft documentation on custom domains.
https://learn.microsoft.com/en-us/azure/app-service/app-service-web-tutorial-custom-domain?tabs=root%2Cazurecli
https://learn.microsoft.com/en-us/azure/app-service/configure-ssl-bindings

Answer 1

Rohan 0

Hi Alex, we are facing this issue after adding the cname and txt record on GCP DNS. It is not pointing to public IP but to the value that Azure generated once we set up custom domains. The current custom domain we added shows a green tick and validated. But when I hit the subdomain url in the browser it does not give anything.
Should it not bring up the application?

Or do I need additional setup like app gateway or other config on top of this?

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How to configure custom domains on azure web app service and add those in GCP Cloud DNS

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