The startup configuration is the configuration your devices run on when they reboot or power up. The running configuration is the current version of the configuration file the device runs on. The key difference here is that the running configuration file contains all recent changes you've made to the configuration since the last device reboot, while no changes are applied to the startup configuration file.
Every change you make to the device configurations is applied to the running configuration file, which is stored in the device's RAM. So, every time the devices are restarted due to a manual reboot or a power failure, all recent changes that were made to the running configurations will be erased.
Changes are often made to device configurations to fix vulnerabilities or improve performance. Unexpected device reboots will erase all recent changes and open doors to attacks and network outages. To avoid these mishaps, you should make sure that all changes made to the running configuration of devices are copied to the startup configuration.
To view the current versions of the startup and running configurations, use the show startup-config and show running-config commands on a Telnet or PuTTY console. You can then export these configurations, manually compare them against each other, and copy the changes to the startup configuration.
However, in a network comprised of several devices, or even just a few devices having configuration files with a countless command lines, manually comparing and updating startup configurations is a cumbersome task.
Using network configuration management tools, you can easily draw out a comparison of configuration files and identify changes. These tools also enable you to quickly copy running configuration files.
Using Network Configuration Manager, you can compare configurations with Diff View, a feature that differentiates lines that were added, deleted, and modified recently using color codes, making it easier for you to identify changes.
Network Configuration Manager also alerts you if there's a conflict between the running and startup configurations, which you can view from the Dashboard widget or the Inventory. Instantly fix this issue by selecting the device from the Inventory and selecting Sync Configuration in the menu bar.
Download a free, 30-day trial of Network Configuration Manager now to avoid configuration conflicts in your network!