Remembering config register #'s?

binaryhat

How do you guys remember them?

NetworkVeteran

binaryhat wrote: »

How do you guys remember them?

I don't.

I should say, I only remember the 2-3 values I use or see used most frequently. Remembering the settings for normal booting, password recovery, etc. are far more important than remembering "115200 baud".

It is this way with many things in networking. We can't remember everything.

Priston

0x2102 and 0x2142 are the important ones. Haven't had to use them in a while.

binaryhat

The reason why I ask is because Boson's practice ? ask this ? --->see attachment.

instant000

I can only remind you that Boson doesn't know exactly what's on the test, so it is better to cover too much, than not enough.)

You will find sometimes that you'll be practicing with their material, and come upon an explanation that wasn't in your primary text. (The topic would be, but some of the information they give in the explanation will look unfamiliar to you.) You then are off for an hour or so, reading up on things, and labbing it for yourself, to see how it really works.

But, hey, that's how you really learn things, when you put in that extra effort to go for it. When you see that something that *stretches* you out a little bit, beyond the comfort zone.

I should be asleep right now, but I find myself in the middle of an all-nighter going over multicast right now

It is what it is.

Do you remember how it was to get that new toy or game back in the day, and you'd be up all night playing it? That's how I feel when I am in the middle of studying something.

I'd make sure to know the most important and useful ones -- that is, when you need to change the boot-up, in order to do a recovery operation. I've made some mistakes in the past, and had to get in there in order to xmodem an image .... takes a while, even if you up the baud rate.

If you're worried about it, you could just make a memory table, where you fill in half the side, and you quiz yourself on what goes in the blanks on the opposite side. (you can alternate sides)

Hope this helps.

theodoxa

binaryhat wrote: »

How do you guys remember them?

Right now, I only remember a couple (0x2102, 0x2142). For the ICND1, I made a chart (can't find it now or I'd post it) with the Hexadecimal value of each setting (e.g. 9600 Baud, 115200 Baud, Ignore Break, Boot to 1st IOS in Flash, Boot to ROMMON, etc...) Adding these value together would give you the value for the config-register for a combination (e.g. 115200 Baud, Ignore Break, Boot to 1st IOS in Flash).

theodoxa

Baud Rate:

0x1000 = 1200 bps
0x1800 = 2400 bps
0x0800 = 4800 bps
0x0000 = 9600 bps
0x0020 = 19200 bps
0x0820 = 38400 bps
0x1020 = 57600 bps
0x1820 = 115200 bps

Broadcast Address:


0x0000 = 255.255.255.255
0x0400 = 0.0.0.0
0x4400 = Subnet ID
0x4000 = Subnet Broadcast

Boot:


0x0000 ROM Monitor
0x0001 First IOS in Flash
0x0002-F Use boot system command

Miscellaneous:


0x0040 Ignore NVRAM (startup-config)
0x0080 Disable Boot Messages
0x0100 Ignore Console Break
0x0200 Perform Netboot
0x2000 Load ROM after 6 Failed Attempts to Load IOS
0x8000 Ignores NVRAM and Enables Diagnostic Messages

------------------------------------------------------
0x2000 (Load ROM after 6 Failed Attempts to Load IOS)
0x0100 (Ignore Console Break) 
0x0002 (Use boot system command)
0x0000 (9600 Baud)
0x0000 (255.255.255.255 Broadcast)
------------------------------------------------------
0x2102

------------------------------------------------------
0x2000 (Load ROM after 6 Failed Attempts to Load IOS)
0x0100 (Ignore Console Break) 
0x0040 (Ignore NVRAM / startup-config)
0x0002 (Use boot system command)
0x0000 (9600 Baud)
0x0000 (255.255.255.255 Broadcast)
------------------------------------------------------
0x2142

------------------------------------------------------
0x2000 (Load ROM after 6 Failed Attempts to Load IOS)
0x1820 (115200 Baud)
0x0100 (Ignore Console Break) 
0x0002 (Use boot system command)
0x0000 (255.255.255.255 Broadcast)
------------------------------------------------------
0x3922

draught

It's probably not worth your time memorizing all of them when there are more important things you could be learning. I'd remember 0x2102 and 0x2142.