Fedora

Hi,
i'm working on micro$oft windows based networking environment's. i want learn other os than micro$oft windows. i tested FreeBSD & Gnu/Linux (Fedora). both are similar. which of following is best choice for me? for networking? and which of them has future (for e.g not discontinued after 2 years later)? any body has any idea? thanks for helping me.

I use Ubuntu for desktop and multimedia systems and for my Netbook.
I use CentOS (Free Redhat Enterprise Linux) for servers

Both will be around for a while. Ubuntu has LTS versions, which stands for Long Term Support and they do have Server editions and Netbook (atom processor) editions as well...

There are hundreds of Distros here is a good place to learn more: http://distrowatch.com/

what about frebsd or other bsd flavors?
i want be expert on one os. i dont want every year change my platform.

For networking, either will work. As you say, they are very similar. (Purists will foam at the mouth at them being called "similar", but it's true: Mostly the same or compatible programs, in mostly the same places, used mostly the same way.) BSD and Linux implement firewalling very differently though. Again, there's not a clear winner, they're just different. Debian Linux is a common favorite for servers, and has been around in one form or another since 1993 so probably isn't going away very soon. They're sometimes criticized for not changing quickly enough, but this is for support and stability reasons; they do backporting when other distros would just want you to upgrade..