Subdomains, redirections and YSlow

I've created a subdomain to host all my images (e.g. http://images.domain.com, which points to my public_html/images/ folder). When I try to 开发者_JAVA百科access a particular image via the browser, I am getting redirected. For example, I go to http://images.domain.com/foobar.jpg, I am redirected to http://www.domain.com/images/foobar.jpg.

Why would I get redirected? This is causing YSlow to lower my overall grade. Thanks.

Most likely is the web server that's serving the images domain (probably the only web server you have). Without info on the server you're using, it's impossible to tell you how to fix it, but it's definitely a configuration option in the server.