Nagios - Backup

I have got access to Nagios machine & I am new to this. Somone was already working on it and it is monitoring many more than 500+hosts and plenty of config files available in various folders.

How do i find out if my Nagios configuration files are backed up or not ? if not what are the methods i can do a regular backup ? cron/rsynch/scp ???

Yes, you can do a backup in a way you’ve mentioned.

How to see where are all config files? Don’t know. They should be organized in /etc/nagios where usually config files reside. It would be best if you could ask that person who managed it where are all config files.