Chapter 18 Troubleshooting : ­Troubleshooting tools : FortiOS diagnostics : The execute tac report command
  
The execute tac report command
exec tac report is an execute command that runs an exhaustive series of diagnostic commands. It runs commands that are only needed if you are using certain features like HA, VPN tunnels, or a modem. The report takes a few minutes to complete due to the amount of output generated. If you have your CLI output logged to a file, you can run this command to familiarize yourself with the CLI commands involved.
When you call Fortinet Customer Support, you will be asked to provide information about your unit and its current state using the output from this CLI command.