I think the answer should be D.
It will try to boot from flash memory then look for IOS image from TFTP
server (booting from network), and then lastly from ROM. However it is all
depends on how boot command in startup configuration file is set up,
Yet, I don't think anyone wants the set up otherwise...
Maybe the following will clear things up.
Router Start-Up Sequence
1. POST : When a router is powered on, the first thing it does is
Power-On-self-Test.
2. Then the bootstrap program is executed from ROM to find the Cisco IOS (by
defualt, IOS image (which is operating system) will be earched in flash
memory).
3. Once an IOS image is found, it will be loaded in to RAM. However, if no
vaild image can be found, the router will revert to what is known as ROM
Montor mode. (This is a special Configuration mode tjat can be used to
install or upgrade an IOS image).
4. Once a valid IOS image file has been loaded, the router will search for a
valid configuration file. Normally, the configuration file should be
located in NVRAM. Once it is found, it also loaded into RAM and processed
by line by line. However, if a valid configuration file cannot be found in
NVRAM, the router will run the System Configuration Dialog.
But what happens when the IOS image file is damaged or missing! Then the
router somehow has to find the IOS image from other source.
So how the router know where to search?
It depends on the value of the configuration register, a 16 bit value stored
in NVRAM. The last four bits which is called boot field controls where the
router tries to load the operating system from.
The default value is 0x2102, which means the router will load the IOS image
from flash memory or whatever is specified by the boot commmand in the
startup configuration file.
As long as the configuration registar is set to its default value, the
router will look to the startup configuration file to determine its boot
method. Specially, the router looks for a boot command within the startup
configuration file.
The boot command specifies the order in which the router searches for the
location of IOS image. Here, one can decide in which order the router will
search for the IOS image by using boot system command. Even though there
are 3 choices (ROM, flash memory, TFTP server), one should set flash memory
first then TFTP server. It is not a good idea to rely on the IOS image from
ROM because this version of IOS is not upgradable and has the least amount
if functionality.
I hope this helps to answer your question....
(You can check Chapter 5 Cisco Router Basic from Exam Prep Routing and
Switching ISBN 1-57610-440-0. What I wrote above is literally taken out of
chapter 5)......
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=12080&t=12012
--------------------------------------------------
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
