Configuration register 0x2102: On a Cisco router, what does a configuration register value of 0x2102 instruct the device to do during boot?

Introduction / Context:
The configuration register is a 16-bit value that directs how a Cisco router boots. The most common setting, 0x2102, tells the device to load the IOS from flash and the startup-config from NVRAM.

Given Data / Assumptions:

• Configuration register = 0x2102.
• Standard Cisco IOS boot process.

Concept / Approach:
0x2102 is the factory default. It specifies: use the console speed 9600, load IOS image from flash, and load the startup-config from NVRAM. Alternative values (0x2142) ignore NVRAM (for password recovery); 0x2100 boots ROMMON; 0x2101 boots RXBOOT.

Step-by-Step Solution:

Verification / Alternative check:
Change register with 'config-register' command in global config or 'confreg' in ROMMON if needed.

Why Other Options Are Wrong:
ROMMON: Value 0x2100. Password recovery: Value 0x2142 ignores NVRAM. TFTP boot: Requires boot system command + TFTP, not default 0x2102.

Common Pitfalls:
Misinterpreting 0x2142 vs 0x2102. 2142 is used for recovery, 2102 is default normal operation.

Final Answer:
Tells the router to look in NVRAM for the boot sequence