Cache-Control header default to no-cache on subsequent request when using HttpCacheControlPolicy about cachecow HOT 2 CLOSED

Update:

Without using HttpCacheControlPolicy attribute, the default cache config like the code below also only applied on the first request as "Cache-Control: no-transform, must-revalidate, max-age=600". The subsequent request will be "304 Not Modified" with "Cache-Control: no-cache".

        cachingHandler.CacheControlHeaderProvider = (request, cfg) =>
        {
            return new System.Net.Http.Headers.CacheControlHeaderValue()
            {
                Private = false,
                MustRevalidate = true,
                NoTransform = true,
                MaxAge = TimeSpan.FromSeconds(600)
            };
        };

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The behaviour is correct. Cache Header directives are irrelevant for a 304 response since the cache headers must be sent with the original response:

If the status code is 304 (Not Modified), the cache uses the entity- body stored in the cache entry as the entity-body of this outgoing response.

As you can see, there is no mention of headers here. Hope this helps.

In terms of examples outside, sites implement 304 differently. I have seen one that sends cache control and another only ETag. As I said the headers are irrelevant.

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