What does the command 'copy startup running (merge)' do to the running configuration?

The command 'copy startup running (merge)' is designed to integrate the settings from the startup configuration into the currently active running configuration. When this command is executed, it does not replace the running configuration but instead blends the parameters defined in the startup configuration with those already present in the running configuration. This is particularly useful when you want to preserve existing configurations while updating or adding new elements from the startup configuration.

This merging process allows network administrators to maintain a continuity of settings and ensures that any new configurations are incorporated without losing existing functionality. The command processes the startup configuration file and applies its parameters on top of the current configuration, meaning any overlapping settings would be updated while those unique to either configuration would be retained.