A firewall keeps a “startup” configuration file in Flash memory. These configuration commands are not lost after a reload or power failure.
As soon as a firewall boots up, the startup configuration commands are copied to the “running” configuration file in RAM (volatile) memory. Any command that is entered or copied into the running configuration is also executed at that time.
As you enter configuration commands, be aware that they are present only in the temporary running configuration. After you have verified the operation of the new configuration commands, you should be sure to save the running configuration into Flash memory. This preserves the configuration in case the firewall reloads later.
You can enter ...