In Linux, /etc directory contains important system-related or application-specific configuration files. Especially in a server environment, it is wise to back up various server configurations in /etc directory regularly, to save trouble from any accidental changes in the directory, or to help with re-installation of necessary packages. Better yet, it is a good idea to “version control” everything in /etc directory, so that you can track configuration changes, or recover from a previous configuration state if need be.

via How to version control /etc directory in Linux – Linux FAQ.