Cisco devices store commands in two configuration files:
·
startup configuration
·
running configuration
Difference between a running configuration and a startup configuration.
Your devices run under the startup configuration when they reboot or turn on. The configuration file that the device is now running on is known as the running configuration. The main distinction is that although no modifications are made to the startup configuration file, the running configuration file incorporates all recent configuration changes you've made since the last device reboot.
Why do startup and running configurations need to be in sync?
The running configuration file, which is kept in the
device's Memory, is updated whenever you make a modification to the
configurations of the device. Consequently, any recent modifications to the
running configurations that were made will be lost every time the devices
restart as a result of a manual reboot or a power outage.
Device configurations are frequently changed to address
flaws or boost performance. Rebooting a device unexpectedly will remove all previous
changes, leave it vulnerable to assaults, and cause network outages. You should
make sure that all modifications made to the running configuration of devices
are replicated to the starting configuration in order to prevent similar
errors.
How do you copy the running configuration to the startup configuration?
The running configuration will immediately receive the
command you type in the global configuration mode. All configured commands will
be lost if a device loses power since a running configuration is stored in RAM.
You must duplicate your existing configuration into the
startup configuration in order to prevent this scenario. All configuration
changes are saved even if a device loses power since a startup configuration is
kept in nonvolatile memory.
Use the show startup-config and show running-config commands
on a Telnet or PuTTY console to see the most recent iterations of the startup
and running configurations. Then you may manually compare these configurations
to one another, export them, and copy the modifications to the startup
configuration.
You must enter the command copy running-configuration
startup-configuration in order to copy your running configuration into the
startup configuration.
Router#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
Router#