This article will discuss some of the issues about performing live web cast. Why do you want to go live, bit rate, encoders, spectators, etc? You will have a better understanding of the webcast live and get some alternatives to hiring an expensive CDN for onetime events.
Know your audience
If this is a corporate event, then it's likely your attendees will be asked to attend. But if this is a concert or sporting event, be sure to know who your audience is and if they will be able to attend. It would be better to offer a concert as a pay-per-view or VOD event that people can watch it at your leisure.
Image Source: Google
Know your encoding options
First choose whether this be events Windows Media or Flash. How Real Media (really, does anyone use Real Media anymore?). How to QuickTime? It gained popularity because of the iPhone, this problem is not too many providers support Darwin live streaming (not yet, check with them for 6 months ahead).
Once you have selected format, choose the encoder. Flash Live Encoding you can use the Flash Live Encoder from Adobe and high end computers. This product is OK for most consumer applications. You really limited to the horsepower of your computer. There is no Mac version available so you have to be on a Windows machine.