ircd - are there more than one?

[Dave Logan <icdlogan@xxxxxxxxxxxxx>]

my task is to install the latest ircd.  we currently run irc2.8.21 on a
privately managed and accessible worldwide network.  i'm not sure which
server software i should download.  my research has turned up server
software for EFnet, IRCnet, Undernet, DALnet, etc.  i suppose i'd want
to use the latest release of the server software that would replace our
current version.
 if i do indeed need to ensure that i acquire the correct server
software than
1. how can i find out what server software type (ie EFnet, Undernet,
etc) our current 2.8.21 is?

tia dave logan icdlogan@xxxxxxxxxxxxx