Technical Documentation

Understanding Configuration Files for EX-series Switches

A configuration file stores the complete configuration of a switch. The current configuration of a switch is called the active configuration. You can alter this current configuration and you can also return to a previous configuration. For more information, see Configuration Files Terms.


JUNOS software saves the 50 most recently committed configuration files on the switch so that you can return to a previous configuration. The configuration files are named:

  • juniper.conf.gz—The current active configuration.
  • juniper.conf.1.gz to juniper.conf.49.gz—Rollback configurations.

To make changes to the configuration file, you have to work in the configuration mode in the CLI or use the configuration tools in the J-Web interface. When making changes to a configuration file, you are viewing and changing the candidate configuration file. The candidate configuration allows you to make configuration changes without causing operational changes to the active configuration or causing potential damage to your current network operations. Once you commit the changes made to the candidate configuration, the system updates the active configuration.