CentOS Directory Server is an application that can run on Centos 4, CentOS 5 and even HP-UX and Solaris. To better understand what Directory Server is, you may want to read this page: http://www.centos.org/docs/5/html/CDS/ag/8.0/Introduction_to_This_Reference_Guide-DS_Overview.html. 

 

First, you have to enable the "extras" yum repository. You'll probably want to read the installation guide here: http://www.centos.org/docs/5/html/CDS/install/8.0/ and the other guides you'll find under "CentOS Directory Server 8.0" here: http://www.centos.org/docs/5/.