Comprehensive Technical Explanation:

A Firebox backup image (.fbi file) provides an exact, cryptographic, binary snapshot of the appliance's complete operating state at the moment of creation. Unlike an export of a standard configuration file (.xml) created in Policy Manager—which retains only structural XML policy definitions, aliases, and general network configurations—a backup image encapsulates the full device flash file system.

This comprehensive snapshot includes:

1. The running Fireware operating system version.

2. The active configuration file (firewall.xml).

3. The installed WatchGuard Feature Key.

4. Local user account databases and administrative credentials.

5. All installed and imported public and private X.509 security certificates (such as web server certificates, intermediate and root CA chains, and the Firebox Proxy Authority certificate and private key used for HTTPS deep inspection).

Because the backup image archives the private keys along with the imported certificates, restoring a backup image completely re-establishes all VPN Phase 1/2 cryptographic trust relationships and SSL/TLS inspection authority without requiring administrators to manually re-import PKI certificates.