Single endpoint with multiple routes are not routing traffic as expected

Question

Single endpoint with multiple routes are not routing traffic as expected

Ross Watson 0

I have an Azure Front Door endpoint which contains two routes, each route has the same domains.

The first route will route traffic to my CMS application.
The second route will route traffic to my CMS Admin application.

Azure Front Door Endpoint:
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Route 1 - to CMS application
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Route 2 - to CMS Admin application

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Now to test this I have custom error turned off for the CMS application and not for the CMS Admin application,

When I browse: domain.com/ I am successful routed to my CMS application.

When I browse: domain.com/admin/login.aspx, I am routed to a default ASP.NET error page so I can see that traffic is still hitting the CMS application and not the CMS Admin application.

I have created a separate endpoint that using the domains like admin.domain.com and pointed it to the same origin group as the second route, just with /* as the path and I am able to browse admin.domain.com/admin/login.aspx and the application load as expected.

This proves that the CMS Admin application does in fact works. The origin and origin group are working as expected.

It just seems like the routes in the endpoint is not working as expected and I cannot find a solution to the problem.

Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-18T19:49:57.3566667+00:00
Hi @Ross Watson

I tested your scenario on my end, and it successfully routed the traffic.

Azure front door endpoint:

Route 1:

Route 2:

when i browse: <frontdoorendpoint_url>/

when i browse: <frontdoorendpoint_url>/admin/index.html

Could you try this once if the issue is not resolved?
Enable the diagnostics log to check the Front Door access logs and see how the request is going to the backend origin.
Refer this doc how to enable the diagnostics logs in front door:
https://learn.microsoft.com/en-us/azure/frontdoor/standard-premium/how-to-logs#configure-logs

After enable logs try this below command

AzureDiagnostics | where ResourceProvider == "MICROSOFT.CDN" and Category == "FrontDoorAccessLog" | project TimeGenerated, requestUri_s ,originUrl_s,httpStatusDetails_s,httpStatusCode_s

Can you please check the requestUri in the output.

Kindly let us know if the above helps or you need further assistance on this issue.
Ross Watson 0 Reputation points

2025-03-19T07:39:48.33+00:00

I have enabled the logs and the origin url and request uri look correct, but it is still throwing a 404 page.

I have made my app service public and if I browse the origin url directly the application works as expected:

When I browse the origin url directly, but intentionally use a non-existing page, I get the 404 page I am expecting as the admin application has custom error enabled:

However, when I browse the request uri I am getting the following. This is why I believe traffic is still being routed to the cms application as I have custom errors turned off on that application:
Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-19T15:55:10.2133333+00:00

Hello @Ross Watson,

Could you please share the below details in the private message.
How is the origin configured in the AFD? What is the origin type, host name & host header? Also how is the health probe configured?
Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-20T18:50:52.6066667+00:00

Hello @Ross Watson,

Could you please share the below details in the private message. How is the origin configured in the AFD? What is the origin type, host name & host header? Also how is the health probe configured?

1 answer

Your answer

Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-18T19:49:57.3566667+00:00

Hi @Ross Watson

I tested your scenario on my end, and it successfully routed the traffic.

Azure front door endpoint:

Route 1:

Route 2:

when i browse: <frontdoorendpoint_url>/

when i browse: <frontdoorendpoint_url>/admin/index.html

Could you try this once if the issue is not resolved?
Enable the diagnostics log to check the Front Door access logs and see how the request is going to the backend origin.
Refer this doc how to enable the diagnostics logs in front door:
https://learn.microsoft.com/en-us/azure/frontdoor/standard-premium/how-to-logs#configure-logs

After enable logs try this below command

AzureDiagnostics | where ResourceProvider == "MICROSOFT.CDN" and Category == "FrontDoorAccessLog" | project TimeGenerated, requestUri_s ,originUrl_s,httpStatusDetails_s,httpStatusCode_s

Can you please check the requestUri in the output.

Kindly let us know if the above helps or you need further assistance on this issue.
Ross Watson 0 Reputation points

2025-03-19T07:39:48.33+00:00

I have enabled the logs and the origin url and request uri look correct, but it is still throwing a 404 page.

I have made my app service public and if I browse the origin url directly the application works as expected:

When I browse the origin url directly, but intentionally use a non-existing page, I get the 404 page I am expecting as the admin application has custom error enabled:

However, when I browse the request uri I am getting the following. This is why I believe traffic is still being routed to the cms application as I have custom errors turned off on that application:
Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-19T15:55:10.2133333+00:00

Hello @Ross Watson,

Could you please share the below details in the private message.
How is the origin configured in the AFD? What is the origin type, host name & host header? Also how is the health probe configured?
Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-20T18:50:52.6066667+00:00

Hello @Ross Watson,

Could you please share the below details in the private message. How is the origin configured in the AFD? What is the origin type, host name & host header? Also how is the health probe configured?

Answer 1

Hi @Ross Watson

From your screenshots, I can say that the root cause of your issue is the empty origin host header.

Let us first understand what origin host header does. Requests that are forwarded by Azure Front Door to an origin will include a host header field that the origin uses to retrieve the targeted resource.

For example, a request made for www.contoso.com will have the host header www.contoso.com. If the request was made for www.contoso.com, and your origin contoso-westus.azurewebsites.net has an empty header field, Front Door will set the host header as www.contoso.com.

Most app backends (Azure Web Apps, Blob storage, and Cloud Services) require the host header to match the domain of the backend. However, the frontend host that routes to your origin will use a different hostname such as www.contoso.net.

If your origin requires the host header to match the origin hostname, make sure that the origin host header includes the hostname of the origin.

Refer: https://learn.microsoft.com/en-us/azure/frontdoor/origin?pivots=front-door-standard-premium#origin-host-header

You are using Azure App service as your backend, and you also mentioned that there is no custom domain configured on your App service. Now, if the origin host header is kept empty, the AFD will forward the request including a host header as your custom domain, but it is not configured on your App service and hence it will not match with your App service domain and eventually fail with 404 not found error. Because the App Service doesn't recognize the custom domain and rejects all incoming requests for this host name. It can't determine where to route the request.

Please don’t forget to close the thread by clicking "Accept the answer" wherever the information provided helps you, as this can be beneficial to other community members.
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Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-25T22:22:17.49+00:00

Hi @Ross Watson

Following up to see if the above answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.
Rohith Vinnakota 4,005 Reputation points Microsoft External Staff

2025-03-26T17:53:27.36+00:00

Hi @Ross Watson

Following up to see if the above answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

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Single endpoint with multiple routes are not routing traffic as expected

1 answer

Your answer