Merge pull request #196031 from JackStromberg/patch-63

Header behavior

Author: v-regandowner

articles/application-gateway/application-gateway-faq.yml

@@ -131,6 +131,9 @@ sections:
           
       - question: Does Application Gateway V2 support proxying requests with NTLM authentication?
         answer: No. Application Gateway V2 doesn't support proxying requests with NTLM authentication.
+        
+      - question: Why are some header values not present when requests are forwarded to my application?
+        answer: Request header names can contain alphanumeric characters and hyphens. Request header names containing other characters will be discarded when a request is sent to the backend target. Response header names can contain any alphanumeric characters and specific symbols as defined in [RFC 7230](https://tools.ietf.org/html/rfc7230#page-27), with the exception of underscores (\_).
 
       - question: Does Application Gateway affinity cookie support SameSite attribute?
         answer: |
@@ -140,7 +143,7 @@ sections:
           
       - question: What is considered an active listener versus inactive listener?
         answer: |
-          An active listener is a listener that is associated to a rule **and** sending traffic to a backend pool. Any listener that **only** redirects traffic is not an active listener. Listeners associated with redirect rules are not considered active. If the redirect rules is a path-based rule, then all the paths in that redirect rule must be redirecting traffic, else the listener is considered active. See [Azure subscription and service limits, quotas, and constraints](../azure-resource-manager/management/azure-subscription-service-limits.md#application-gateway-limits) for individual component limit details. 
+          An active listener is a listener that is associated to a rule **and** sending traffic to a backend pool. Any listener that **only** redirects traffic is not an active listener. Listeners associated with redirect rules are not considered active. If the redirect rule is a path-based rule, then all the paths in that redirect rule must be redirecting traffic, else the listener is considered active. See [Azure subscription and service limits, quotas, and constraints](../azure-resource-manager/management/azure-subscription-service-limits.md#application-gateway-limits) for individual component limit details. 
       
   - name: Performance
     questions:
@@ -383,7 +386,7 @@ sections:
         answer: |
           Yes, the Application Gateway v2 SKU supports Key Vault. For more information, see [TLS termination with Key Vault certificates](key-vault-certs.md).
           
-      - question: How do I configure HTTPS listeners for .com and .net sites? 
+      - question: How do I configure HTTPS listeners for .com and .NET sites? 
         answer: |
           For multiple domain-based (host-based) routing, you can create multisite listeners, set up listeners that use HTTPS as the protocol, and associate the listeners with the routing rules. For more information, see [Hosting multiple sites by using Application Gateway](./multiple-site-overview.md).
           

articles/application-gateway/rewrite-http-headers-url.md

@@ -283,7 +283,8 @@ In the case of a URL redirect, Application Gateway sends a redirect response to
 
 - If a response has more than one header with the same name, then rewriting the value of one of those headers will result in dropping the other headers in the response. This can usually happen with Set-Cookie header since you can have more than one Set-Cookie header in a response. One such scenario is when you are using an app service with an application gateway and have configured cookie-based session affinity on the application gateway. In this case the response will contain two Set-Cookie headers: one used by the app service, for example: `Set-Cookie: ARRAffinity=ba127f1caf6ac822b2347cc18bba0364d699ca1ad44d20e0ec01ea80cda2a735;Path=/;HttpOnly;Domain=sitename.azurewebsites.net` and another for application gateway affinity, for example, `Set-Cookie: ApplicationGatewayAffinity=c1a2bd51lfd396387f96bl9cc3d2c516; Path=/`. Rewriting one of the Set-Cookie headers in this scenario can result in removing the other Set-Cookie header from the response.
 - Rewrites are not supported when the application gateway is configured to redirect the requests or to show a custom error page.
-- Header names can contain any alphanumeric characters and specific symbols as defined in [RFC 7230](https://tools.ietf.org/html/rfc7230#page-27). We don't currently support the underscore (\_) special character in Header names.
+- Request header names can contain alphanumeric characters and hyphens. Headers names containing other characters will be discarded when a request is sent to the backend target.
+- Response header names can contain any alphanumeric characters and specific symbols as defined in [RFC 7230](https://tools.ietf.org/html/rfc7230#page-27), with the exception of underscores (\_).
 - Connection and upgrade headers cannot be rewritten
 - Rewrites are not supported for 4xx and 5xx responses generated directly from Application Gateway