Technical Tip: Understanding FortiGate Configuration File Format

The configuration file contains only non-default settings and select important default settings to minimize the backup size.

Unencrypted configuration file:

To restore an unencrypted configuration file, only the FortiGate model has to match. If the firmware is different, FortiGate will attempt to upgrade the configuration, which may cause unexpected config changes. It is highly recommended to match the firmware on FortiGate with the firmware listed in the configuration file.

Encrypted configuration file:

To restore an encrypted config file, the model, firmware, and password must all match.

VDOM configuration file:

To download the VDOM-only config, go to Username -> Configuration -> Backup -> Ccope: VDOM -> VDOM: vdom-name -> OK.

Related articles:

Technical Tip: How to load/convert a FortiGate configuration file from one unit to another (file conversion for a different model) 

Technical Tip: How to download FortiGate configuration file & Debug log from GUI