Not sure if this is the correct forum for this question...

We curretnly have a mixed tree with several 4.2 servers (DS 6.21) and a
few 6.5 SP3 (eDir 8.7.3).

Can I install a new 4.2 server into the tree? The server hardware is
kind of old and will not support 6.5. We are in the process of
purchasing new hardware but, it is going to take some time.