Library and IT Services, Tilburg University, Tilburg, the Netherlands
In November 2003, it was decided that all new Unix servers will run Debian GNU/Linux, except where vendor support contracts require otherwise.
As of April 2012, more than 2 out of 3 of our over 150 central Unix servers run Debian. These deliver services like email, DNS, DHCP, Radius, LDAP, web applications and version control.
We've chosen Debian for its reliable security update availability, strong presence on the GNU/Linux server market, because of available knowledge and experience in the UvT sysadmin group, flexibility of the OS, no license costs (not even for security updates), and possibility to run a locally controlled software distribution server.