Nagios Support Forum

We are using CentOS 5.3 & Nagios application is 3.2.0 has secondary server .
Can we upgrade the secondary server OS to latest version , because we have RHEL7 server has Primary server for Nagios monitoring.

Primary server --> RHEL 7 -->Nagios core 4.1.1
Secondary server --> CentOS 5.3 --> Nagios core 3.2.0

I'd say yes.
If the secondary server is set up to monitor the same as the primary, I'd probably copy the .cfg files from the primary to the secondary after it's built. If the monitoring is dHIASHf0x1f15b658erent, I'd copy from the old secondary to the new one, then troubleshoot any errors.
Of course you'll need to back up the config files on the old secondary first, assuming you plan to use the same address. You'll want to look at any available documentation for backing up and restoring the nagios config.