The Routing Engine is responsible for processing management traffic and maintaining routing tables. It does not process CoS marked traffic, which is handled by the forwarding plane, nor does it forward transit traffic.

To navigate to configuration mode from an operational mode prompt, you can use the 'configure' command or the 'edit' command. The 'configure' command switches directly to the configuration mode, while 'edit' is used to enter a specific part of the configuration hierarchy directly. The 'quit' and 'exit' commands are used to leave a mode or session, not to enter configuration mode.

In Junos OS, the keyboard shortcut to move to the start of the line is Ctrl+a. This is a common keyboard shortcut in various command-line environments and follows the behavior in many Unix-like systems.