We have following installed .
A)Update Rollup 15 for 2 CAS and 2 mailbox servers.
Current version: 08.03.0389.002
we need to go for
Update Rollup 19 for 2 CAS and 2 mailbox servers.
Updated version: 08.03.0459.000
please let me know the steps, do we need to put the server in maintainance mode or just install the roll ups.