Azure front with application gateway with multiple different backend servers

JUNAID HAROON 40 Reputation points
2026-02-02T12:46:40.0766667+00:00

Azure-front-door.jpgHi,

I need to publish my three different websites through Azure Front Door and Application Gateway. A high-level diagram is attached herewith. I tested one website initially, and it was working fine. However, when I added two more applications, I noticed an issue. The front door or application gateway is not redirecting user traffic to the correct application.

Suppose user want to access Em.abc.com or Sti.abc.com front door is redirecting traffic to Gell.abc.com.

Please help me out. What could be the reason?

Azure Front Door
Azure Front Door

An Azure service that provides a cloud content delivery network with threat protection.

Answer accepted by question author
Praveen Bandaru 11,800 Reputation points Microsoft External Staff Moderator
2026-02-03T12:27:27.2866667+00:00

Hello JUNAID HAROON

I see that you're experiencing an issue with Azure Front Door not properly routing traffic to the various backends for your websites.
I understand that your application Gateway backend consists of three servers, each hosting different applications. Now, you want to set up a Front Door in front of the application Gateway to allow direct access, with the Application Gateway serving as the backend. To do this, you need to properly configure the Application Gateway, including setting up backend pools for the three servers and defining specific rules for each one.For the listeners configuration, you should deploy three dedicated listeners, one for each backend pool, and configure the host name for each backend in the listener settings.

Test the application gateway to verify if it is functioning as expected. If everything works correctly, you can then add the application gateway as the backend for the front door.

For the front door configuration, deploy one origin group with a single origin. In the origin settings, select Custom for the origin type, enter the application gateway's private IP as the Host Name, and leave the Origin Host header blank. Check the below screen shot for more understanding:

User's image

Disable certificate subject name validation and enable the private link feature.

Once you have configured the Custom Domains in the front door, please route the traffic through it, test the setup, and let me know the results.

Hope the above answer helps! Please let us know do you have any further queries.

Please do consider to “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

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Answer accepted by question author

AI answer

2026-02-02T12:47:22.26+00:00

The issue you are experiencing with Azure Front Door and Application Gateway not redirecting traffic to the correct application could be due to several reasons related to the configuration of routing rules and backend pools. Here are some potential causes and solutions to consider:

  1. Routing Rules: Ensure that you have correctly configured the routing rules in Azure Front Door. Each domain (Em.abc.com, Sti.abc.com, Gell.abc.com) should have its own routing rule that points to the appropriate backend pool. If the rules are not set up correctly, traffic may be misrouted.
  2. Backend Pools: Verify that the backend pools for each application are correctly defined and that they include the correct endpoints. Each backend pool should correspond to the respective application.
  3. Path-Based Routing: If you are using path-based routing, ensure that the paths specified in the routing rules do not overlap in a way that causes confusion in traffic direction.
  4. Health Probes: Check the health probes for each backend. If a backend is marked as unhealthy, Front Door may not route traffic to it, leading to unexpected behavior.
  5. Caching Issues: Sometimes, caching in Azure Front Door can cause issues with routing. You might want to clear the cache or adjust caching settings to ensure that users are directed to the correct application.
  6. DNS Configuration: Ensure that your DNS settings are correctly pointing to the Azure Front Door instance. Incorrect DNS settings can lead to traffic being routed incorrectly.

By reviewing these configurations, you should be able to identify the cause of the misrouting and correct it accordingly.

References:

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