Server requirements for deploying a compiled Flex or Flash application (SWF file)
A normal web server will do.
Flex or Flash applications are compiled to SWF format. You can deploy SWF file on a normal web server.
SWF files are downloaded on to the the client and will run on the Flash Player. So there are no specific requirements for hosting or deploying a Flex application. A normal web server which is used to deploy a HTML page is sufficient for deploying the SWF files.
In the URL below there is a detailed description on how to deploy a Flex application. You will find very useful.