how to check if a website is down!

So many of you try to visit my website or other travel websites and think you mis-typed a url while in fact it is down, this is usually a dns problem but can easily determined which it is by using the following site: http://tinyurl.com/44ultrg

basically it is a website that after you enter a url it tells you if the website is down for them too or is it just on your pc, if it is down for them there is not much you can do but if it isn't you can try changing your dns settings (I'll post a guide soon but for now Google it)