When a router is booted up, it goes through the following sequence (see Figure 9-1):
The router checks its hardware with a power-on self test (POST).
The router loads a bootstrap code.
The Cisco IOS Software is located and loaded using the information in the bootstrap code.
The configuration is located and loaded.
After this sequence completes, the router is ready for normal operation.
When the router is started for the first time, it does not have an initial configuration. The IOS will execute a question-derived initial configuration routine called setup mode. You can enter setup mode at any time by entering the setup privileged EXEC command. Setup mode configures the following:
Initial global parameters, ...