Merge pull request #233409 from duongau/afdtroubleshooting

Azure Front Door - Troubleshooting issue - freshness update

Author: prmerger-automator[bot]

articles/frontdoor/troubleshoot-issues.md

@@ -1,11 +1,11 @@
 ---
 title: Troubleshoot Azure Front Door common issues
-description: In this tutorial, you'll learn how to troubleshoot some of the common problems that you might face for your Azure Front Door instance.
+description: In this article, you learn how to troubleshoot some of the common problems that you might face for your Azure Front Door instance.
 services: frontdoor
 author: duongau
 ms.service: frontdoor
 ms.topic: how-to
-ms.date: 11/12/2021
+ms.date: 04/04/2023
 ms.author: duau
 ---
 
@@ -15,35 +15,35 @@ This article describes how to troubleshoot common routing problems that you migh
 
 ## Other debugging HTTP headers
 
-You can request Azure Front Door to return more debugging HTTP response headers. For more information, see [optional response headers](front-door-http-headers-protocol.md#optional-debug-response-headers).
+You can request Azure Front Door to return extra debugging HTTP response headers. For more information, see [optional response headers](front-door-http-headers-protocol.md#optional-debug-response-headers).
 
 ## 503 or 504 response from Azure Front Door after a few seconds
 
 ### Symptom
 
-* Regular requests sent to your backend without going through Azure Front Door are succeeding. Going via Azure Front Door results in 503 or 504 error responses.
+* Regular requests sent to your backend without going through Azure Front Door are succeeding. Going through the Azure Front Door results in 503 or 504 error responses.
 * The failure from Azure Front Door typically appears after about 30 seconds.
 * Intermittent 503 errors appear with "ErrorInfo: OriginInvalidResponse."
 
 ### Cause
 
-The cause of this problem can be one of three things:
+The cause of this issue can be one of three things:
 
-* Your origin is taking longer than the timeout configured to receive the request from Azure Front Door. The default is 30 seconds.
+* Your origin is taking longer than the timeout configured to receive the request from Azure Front Door. The default timeout is 30 seconds.
 * The time it takes to send a response to the request from Azure Front Door is taking longer than the timeout value.
 * The client sent a byte range request with an **Accept-Encoding** header, which means compression is enabled.
 
 ### Troubleshooting steps
 
-* Send the request to your backend directly without going through Azure Front Door. See how long your backend usually takes to respond.
-* Send the request via Azure Front Door and see if you're getting any 503 responses. If not, the problem might not be a timeout issue. Contact support.
-* If requests going through Azure Front Door result in a 503 error response code, configure **Origin response timeout (in seconds)** for Azure Front Door. You can extend the default timeout to up to 4 minutes, which is 240 seconds. To configure the setting, go to overview page of the Front Door profile. Select **Origin response timeout** and enter a value between *16* and *240* seconds.
+* Send the request to your origin directly without going through Azure Front Door. See how long your origin normally takes to respond.
+* Send the request through Azure Front Door and see if you're getting any 503 responses. If not, the problem may not be a timeout issue. Create a support request to troubleshoot the issue further.
+* If requests going through Azure Front Door result in a 503 error response code then configure the **Origin response timeout** for Azure Front Door. You can increase the default timeout to up to 4 minutes (240 seconds). To configure the setting, go to overview page of the Front Door profile. Select **Origin response timeout** and enter a value between *16* and *240* seconds.
 
     :::image type="content" source="./media/how-to-configure-endpoints/origin-timeout.png" alt-text="Screenshot of the origin timeout settings on the overview page of the Azure Front Door profile.":::
 
-* If the timeout doesn't resolve the issue, use a tool like Fiddler or your browser's developer tool to check if the client is sending byte range requests with **Accept-Encoding** headers. Using this option leads to the origin responding with different content lengths.
+* If increasing the timeout doesn't resolve the issue, use a tool like Fiddler or your browser's developer tool to check if the client is sending byte range requests with **Accept-Encoding** headers. Using this option leads to the origin responding with different content lengths.
 
-   If the client is sending byte range requests with **Accept-Encoding** headers, you have two options. You can disable compression on the origin/Azure Front Door. Or you can create a rules set rule to remove **Accept-Encoding** from the request for byte range requests.
+   If the client is sending byte range requests with **Accept-Encoding** headers, you have two options. The first option is to disable compression on the origin or Azure Front Door. The second option is to create a rules set rule to remove **Accept-Encoding** from the request for byte range requests.
 
     :::image type="content" source="./media/troubleshoot-issues/remove-encoding-rule.png" alt-text="Screenshot that shows the Accept-Encoding rule in a rule set.":::
 
@@ -104,7 +104,7 @@ The cause of this problem can be one of three things:
 
 ### Cause
 
-The problem occurs if you didn't configure a routing rule for the custom domain that was added as the frontend host. A routing rule needs to be explicitly added for that frontend host. That's true even if a routing rule was already configured for the frontend host under the Azure Front Door subdomain, which is ***.azurefd.net**.
+The problem occurs if you didn't configure a routing rule for the custom domain that was added as the frontend host. A routing rule needs to be explicitly added for that frontend host. You need to create the rule even if a routing rule was already configured for the frontend host under the Azure Front Door subdomain, which is ***.azurefd.net**.
 
 ### Troubleshooting step
 
@@ -141,7 +141,7 @@ Responses to these requests might also contain an HTML error page in the respons
 
 There are several possible causes for this symptom. The overall reason is that your HTTP request isn't fully RFC-compliant.
 
-An example of noncompliance is a `POST` request sent without either a **Content-Length** or a **Transfer-Encoding** header. An example would be using `curl -X POST https://example-front-door.domain.com`. This request doesn't meet the requirements set out in [RFC 7230](https://tools.ietf.org/html/rfc7230#section-3.3.2). Azure Front Door would block it with an HTTP 411 response. Such requests will not be logged.
+An example of noncompliance is a `POST` request sent without either a **Content-Length** or a **Transfer-Encoding** header. An example would be using `curl -X POST https://example-front-door.domain.com`. This request doesn't meet the requirements set out in [RFC 7230](https://tools.ietf.org/html/rfc7230#section-3.3.2). Azure Front Door would block it with an HTTP 411 response. Such requests don't get logged.
 
 This behavior is separate from the web application firewall (WAF) functionality of Azure Front Door. Currently, there's no way to disable this behavior. All HTTP requests must meet the requirements, even if the WAF functionality isn't in use.