ccna 200 301 udemy

ccna 200 301 udemy.The first two steps are pretty straightforward, but step 3 tells the router to pay attention to the second major method, which tells it which IOS : bootsystem global configuration command to load. This command can be configured multiple times on the router, and each new boot system command is added to the end of the bootsystem command list.Each command can point to a different file in flash memory, along with a different file name and the IP address of the server, telling the router where to look for the IOS image that needs to be loaded. The router attempts to load these IOS images in order, following the order of the configured bootsystem commands.Both Step 2 and Step 3b involve a concept called the "first" I0S file, which needs further explanation.The router numbers the files stored in flash memory, the newer the file, the larger the number. When the router tries step 2 or 2b in the preceding list of steps, it looks in the flash memory for the file numbered 1, then 2, and so on, until it finds the smallest numbered IOS image file, which the router then loads.Interestingly, most routers end up using step 3b to find their IOS image. From the factory, the routers do not have any bootsystem commands already configured; in fact, they do not have any configuration in the boot configuration file. When building and testing the router, the Cisco router loads the only IOS in flash memory and configures the router with a value set to 0x2102, which means the boot field is 0x2. With these settings, the loading process then tries step 3 (because bow I boot field = 2), cannot find the bootsystem command (because the boot configuration is empty), and then follows step 3b, Find the first file in flash memory.Figure 20-4 summarizes several key concepts behind the process of how the router chooses which OS to load. The bootsystem command need not involve the exact file that the router should load. Table 20-3 gives a few examples of commands.11.2 Basic Content 413Table 20-3 Examples of Boot System CommandsBoot System Commands Resultboot system flash Loads the first file in system flash