Final answer:
After the router's IOS loads from flash, it proceeds to load the startup configuration file from NVRAM or enters setup mode if the configuration file is missing.
Step-by-step explanation:
Following the default settings, once the IOS loads from flash on a router, the next step in the router boot sequence is to locate and load the startup configuration file from NVRAM. This configuration file contains the settings used by the IOS to configure the router's interfaces and protocols. If a startup configuration file is not found in NVRAM, the router may enter setup mode, where the user is prompted to provide basic configuration information.