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I'm optimizing my site now following instructions of test. One of recommendations is to not send cookies when static content is requested.
OK, i've created subdomain for my images and other resources. Main domain is and for resources is
But it seems that browser always send cookies obtained from main domain, to its' subdomains. Is it possible to deny doing it?
I'm using ASP.NET 4.0.
No, the only way to prevent it if your site is at the top-level would be to use a completely different domain (like
or swith from to
Technically www is still a subdomain of the main domain. You either need to use an entirely different domain or specially tell whatever is creating the cookies to limit the cookie domain to only your base domain. For example, sets the cookie only for the base domain, whereas sets it for all subdomains as well as the base. It is really the browser that is sending the cookies to the server, and only because the cookie has been set ambiguously.
For the cookie-free domain it makes sense to use a very short name. Google uses e.g., 6 digits plus .com.
We use 4 digits plus .de as the website has a .de domain.
We also don't use a www. in the URL of the static domain to save some letters. 10 http-requests without www. means that we save 40 letters. Not a lot, but why not saving when it's so easy?

In your case something like could be ideal.
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