Where do routers look for IOS configuration

I am getting Contradicting answers from my study material. I thought the boot sequence for the IOS was the following

Flash, NVRAM, TFTP, ROM

But my sources are saying

NVRAM, Flash, TFTP, ROM

Why is that? I thought Flash stored the IOS – I am lost

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Comments

kafifi13

Yes the Flash does store the IOS and NVRAM stores your startup config files.

datchcha

kafifi13 wrote:

Yes the Flash does store the IOS and NVRAM stores your startup config files.

So it is safe to say that a router will look in the following locations during boot for the IOS in this order?

Flash, NVRAM, TFTP, ROM

georgemc

datchcha wrote:

kafifi13 wrote:

Yes the Flash does store the IOS and NVRAM stores your startup config files.

So it is safe to say that a router will look in the following locations during boot for the IOS in this order?

Flash, NVRAM, TFTP, ROM

Are you asking about the configuration file or the IOS image. They're not the same thing. The NVRAM does not contain an IOS image.

datchcha

georgemc wrote:

datchcha wrote:

kafifi13 wrote:

Yes the Flash does store the IOS and NVRAM stores your startup config files.

So it is safe to say that a router will look in the following locations during boot for the IOS in this order?

Flash, NVRAM, TFTP, ROM

Are you asking about the configuration file or the IOS image. They're not the same thing. The NVRAM does not contain an IOS image.

I saw this one question that asked where the IOS configuration and the answer was

NVRAM, FLASH, TFTP, ROM

but i do not user stand that since NVRAM doesn't story to IOS image.

I even found this website http://www.svrops.com/svrops/documents/ciscoboot.htm

Notice the section labeled Located the IOS Software. It lists the same: NVRAM, FLASH, TFTP, ROm.

georgemc

datchcha wrote:

I saw this one question that asked where the IOS configuration and the answer was

NVRAM, FLASH, TFTP, ROM

but i do not user stand that since NVRAM doesn't story to IOS image.

I even found this website http://www.svrops.com/svrops/documents/ciscoboot.htm

Notice the section labeled Located the IOS Software. It lists the same: NVRAM, FLASH, TFTP, ROm.

The IOS image can be in FLASH, TFTP, or ROM. When the router boots, it first looks for "boot system" commands (in the configuration file which in stored in NVRAM) pointing to an IOS Image in other than the default location (FLASH). It then then looks for an image in FLASH, then TFTP and as a last resort boots from the ROM.

datchcha

georgemc wrote:

datchcha wrote:

I saw this one question that asked where the IOS configuration and the answer was

NVRAM, FLASH, TFTP, ROM

but i do not user stand that since NVRAM doesn't story to IOS image.

I even found this website http://www.svrops.com/svrops/documents/ciscoboot.htm

Notice the section labeled Located the IOS Software. It lists the same: NVRAM, FLASH, TFTP, ROm.

The IOS image can be in FLASH, TFTP, or ROM. When the router boots, it first looks for "boot system" commands (in the configuration file which in stored in NVRAM) pointing to an IOS Image in other than the default location (FLASH). It then then looks for an image in FLASH, then TFTP and as a last resort boots from the ROM.

Thanks.