you can manually check 301 redirect is available or not on your site...just remove 'www' from your domain and check whether its redirecting or not?an also check its redirecting to the same url or not?
You can type your URL in search bar. Just type www and non-www for you URL. Look up for the result. It must be same landing page for the result.
they are many plugins for firefox which supports the 301 redirect check. personally, i use the firebug to see it.
You can use these redirect checkers ragepank. com/redirect-check/ internetofficer. com/seo-tool/redirect-check/
any HTTP Header check will go, lots, search on google. Also theres a new tool for 301 redirect, check it out.