diff --git a/src/Zengenti.Contensis.RequestHandler.Application/Middleware/RequestHandlerMiddleware.cs b/src/Zengenti.Contensis.RequestHandler.Application/Middleware/RequestHandlerMiddleware.cs
index 36cfb3c..293a809 100644
--- a/src/Zengenti.Contensis.RequestHandler.Application/Middleware/RequestHandlerMiddleware.cs
+++ b/src/Zengenti.Contensis.RequestHandler.Application/Middleware/RequestHandlerMiddleware.cs
@@ -558,6 +558,13 @@ private async Task<EndpointResponse> GetFriendlyErrorResponse(
 
     private static void EnsureResponseHeadersAndStatusCode(RouteInfo routeInfo, EndpointResponse response)
     {
+
+        response.Headers[Constants.Headers.IsIisFallback] = new List<string>
+                    {
+                        routeInfo.IsIisFallback.ToString().ToLower()
+                    };
+
+
         if (!routeInfo.IsIisFallback)
         {
             if (routeInfo is { ProxyId: not null, BlockVersionInfo: null })
diff --git a/src/Zengenti.Contensis.RequestHandler.Domain/Common/Constants.cs b/src/Zengenti.Contensis.RequestHandler.Domain/Common/Constants.cs
index c43736b..5c11999 100644
--- a/src/Zengenti.Contensis.RequestHandler.Domain/Common/Constants.cs
+++ b/src/Zengenti.Contensis.RequestHandler.Domain/Common/Constants.cs
@@ -49,6 +49,8 @@ public static class Headers
         public const string IisHostname = "x-iis-hostname";
         public const string OrigHost = "x-orig-host";
 
+        public const string IsIisFallback = "x-is-iis-fallback";
+
         public static readonly string[] ConfigHeaders =
         {
             BlockConfig,