The Internal Components of a Cisco Router

To configure and troubleshoot a Cisco internetwork, you need to know the major components of Cisco routers and understand what each one does. Table 7-1 describes the major Cisco router components.

Table 7-1: Cisco router components

Component	Description
Bootstrap	Stored in the microcode of the ROM, the bootstrap is used to bring a router up during initialization. It will boot the router and then load the IOS.
POST (power-on self-test)	Stored in the microcode of the ROM, the POST is used to check the basic functionality of the router hardware and determines which interfaces are present.
ROM monitor	Stored in the microcode of the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting.