Chrome ignores ETag header and just uses cache cache / cache in cache

Question

If I understand correctly, the thread for using ETag works as described now:

• The browser sends a request to the server. Server sends back image from ETag
• Browser saves resource with ETag
• At the next request, the browser sends a request with a header If-None-Matchcontaining the saved ETag.

When returning the response, chrome dev tools says these are my headers

Cache-Control:max-age=7200
Connection:keep-alive
Content-Type:image/png
Date:Thu, 27 Apr 2017 13:42:57 GMT
ETag:"b36f59c868d4678033d318a182658e18371df8f5"
Expires:Thu, 27 Apr 2017 15:42:57 GMT
Server:nginx
Transfer-Encoding:chunked
X-Debug-Token:873c8f
X-Debug-Token-Link:http://localhost:8081/_profiler/873c8f

Now when I reload the page, the new image is not going to. It is saved via the Chrome cache or disk cache, as you can see here

But why is this happening? I sent ETag, so why the browser does not make another request to the server, but uses its own cache?

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2
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Cache-Control:max-age=0, private
Connection:keep-alive
Content-Type:image/png
Date:Thu, 27 Apr 2017 14:44:57 GMT
ETag:"e5b18bdebe44ed4bba3acb6584d9e6a81692ee27"
Expires:Fri, 27 Oct 2017 14:44:57 GMT
Server:nginx
Transfer-Encoding:chunked
X-Debug-Token:3447a6
X-Debug-Token-Link:http://localhost:8081/_profiler/3447a6

Chrome - . nginx

location ~* \.(?:jpg|jpeg|gif|png|ico|cur|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
  access_log off;
  add_header Cache-Control "max-age: 0, must-revalidate";
}

3
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Answer 1

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Answer 2

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@Musterknabe 3:

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2. ( startup.cs) - . .

    public void Configure(IApplicationBuilder app)
    {
        app.UseStaticFiles(new StaticFileOptions
        {
            OnPrepareResponse = ctx =>
            {
                const int durationInSeconds = 0;
                ctx.Context.Response.Headers[HeaderNames.CacheControl] =
                    "must-revalidate,max-age=" + durationInSeconds;
            }
        });
    }

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