Getting @font-face to Work on all Browsers

I’ve tried probably about ten suggestions found all over the web, and this is the only method I’ve found to function universally, across every browser I’ve tested it with.

@font-face {
    font-family: 'NameOfFontFamily';
    src: url('/font/file.eot?') format('eot'),
    url('/font/file.woff') format('woff'),
    url('/font/file.ttf') format('truetype');
}

You can use online font converters to convert an OpenType or TrueType font to *.eot and *.woff as needed. For whatever reason, the “?” appears to be important as well. Not sure about that, I’ll have to look into it further.