Any CCNAs out there? Cisco IOS question...

gwilks98 · 07-27-2007, 12:46 PM

For the CCNA test, how well do I have to know the config-register parameters?

Because they don't use every bit as part of the boot parameters, it's making it tough to memorize ALL the possible numbers you can put in there

Quote:

The lowest four bits (bits 3, 2, 1, and 0) of the 16-bit configuration register form the boot field. The default boot field value is 0x10F. The possible configuration register boot field settings are as follows:

•When the boot field equals 0000, the switch does not load a system image. Instead, it enters ROM-monitor mode from which you can enter ROM-monitor commands to manually load a system image.

•When the boot field equals 0001, the switch loads the first valid system image found in onboard Flash memory.

•When the boot field equals a value between 0010 and 1111, the switch loads the system image specified by boot system commands in the NVRAM configuration. It attempts to boot the image in the order in which you entered the boot system commands. If it cannot boot any image in the BOOT environment variable list, the switch remains in ROM-monitor mode. The exact booting sequence is defined by the ROM monitor.

The function of other bits in the configuration register are as follows:

•Bit 6 (0x0040): Causes system software to clear NVRAM contents.

•Bit 7 (0x0080): Enables OEM bit (not used).

•Bit 8 (0x0100): Disables break.

•Bit 9 (0x0200): Uses secondary bootstrap (not used by the ROM monitor).

•Bit 10 (0x0400): Provides IP broadcast with all zeros (not used).

•Bits 11/12 (0x0800/0x1000): On the Catalyst 5000 and 2926G series switches, provide console line speed: 0/0=9600, 0/1=1200, 1/0=4800, 1/1=2400 (Default is 9600). On the Catalyst 4000 and 2948G series switches, these bits are always set to 0/0 (9600 baud).

•Bit 13 (0x2000): Boots default Flash software if network boot fails (not used).

•Bit 14 (0x4000): IP broadcasts do not have network numbers (not used).

•Bit 15 (0x8000): Enables diagnostic messages and ignores NVRAM contents (not used).

So I'm having trouble making general rules that helps memorize what each config does because of the way they designed it. The second byte is what's killing me with all the possible combinations of configurations.

How detailed does the exam get with this stuff? Am I going to have to convert hex to decimal to binary just to figure out what they're asking? I can remember the default 0x2102, but these things can get hairy quick.

I don't know of an easier way to determine what a config register of 0xDE22 would boot as without breaking it down to binary. (IOS boot, 2ndary bootstrap, IP broadcast using 0's, 2400 baud console port, no network numbers in IP broadcasts and ignore nvram contents/enable diagnostic messages)

Anyone care to share their insight about what's expected?

beatbox32 · 07-27-2007, 03:41 PM

It's been awhile since I took my CCNA (4 years i think), so I'm not sure just how deep they get on the current one. I pulled this info out of my CCIE study book and hopefully it will help. I highlighted the key part that you'll most likely want to memorize:

Quote:

The configuration register is a 16-bit software register in the router, and its value is set using the config-register global configuration command. (Some older routers had a hardware configuration register with jumpers on the processor card, to set bits to a value of 0 or 1.) On most Cisco routers, the default configuration register setting is hexadecimal 2102 (0x2102). Figure 24-6 shows an example binary breakdown of the default value for the configuration register.

Figure 24-6 Binary Version of Configuration Register, Value Hex 2102:

First column is Bit Position, in Decimal.
Second column is Default Binary Value.

15 | 0
14 | 0
13 | 1
12 | 0
11 | 0
10 | 0
09 | 0
08 | 1
07 | 0
06 | 0
05 | 0
04 | 0
03 | 0
02 | 0
01 | 1
00 | 0

The term boot field refers to the low-order 4 bits of the configuration register, because only those 4 bits impact the router’s choice of what software to load. The boot field is often considered as a separate 4-bit value, represented as a single hexadecimal digit. (Cisco represents hexadecimal values by preceding the hex digit[s] with 0x—for example, 0xA would mean a single hex digit A.)

When deciding which software to load, a router first looks at the configuration register’s boot field, using the following logic to determine which to use:
1. If the boot field is hex 0, the router loads ROMMON.
2. If the boot field is hex 1, the router uses RXBOOT mode.
3. For anything else, the router loads an OS based on the configured boot system commands.

I'm working on my CCIE right now, so if you have any questions, feel free to ping me!

gwilks98 · 07-27-2007, 09:04 PM

Cool...I've already got that down. I was just worried they were concerned with memorizing the other more obscure bit placements.

I know someone who passed their CCIE. He said it was the worst 2 years of studying of his life. Good luck to you.

beatbox32 · 07-28-2007, 08:21 AM

Thanks! I've definitely been without a life for the past year and a half. I'm scheduled to take the lab in January. When are you going to sit for the CCNA? Best of luck to you my friend! Let us know how it goes.

gwilks98 · 07-28-2007, 08:51 PM

Quote:

Originally Posted by beatbox32

Thanks! When are you going to sit for the CCNA? Best of luck to you my friend! Let us know how it goes.

I haven't given myself a deadline, but I'm thinking by year end I should be ready. I take my time with this kind of stuff and study it 4 or 5 times before I take the test. A cert is no good to me if all I did was memorize a bunch of test questions and pass the test.

What are you going to use the CCIE for? You work for an ISP?

beatbox32 · 08-01-2007, 12:07 PM

Quote:

Originally Posted by gwilks98

I haven't given myself a deadline, but I'm thinking by year end I should be ready. I take my time with this kind of stuff and study it 4 or 5 times before I take the test. A cert is no good to me if all I did was memorize a bunch of test questions and pass the test.

What are you going to use the CCIE for? You work for an ISP?

Good for you. Too many paper certs these days and the ones who know what they're doing really shine. As far as me, I work for a professional services company (read: consultant) and we're a large Cisco Gold partner. It's good for the company and it's good for my future.

gwilks98 · 08-01-2007, 03:27 PM

The IE I know works for Worldwide. I was looking over the exam details and got a little frightened when I saw how demanding and exhausting it was:

(on top of all that, there are only 2 places in the US where you can take these tests.)

Quote:

Cost
Lab exams cost US$1250 per attempt, not including travel and lodging expenses. Costs may vary due to exchange rates and local taxes (VAT, GST). You are responsible for any fees your financial institution charges to complete the payment transaction.

Lab Environment
The Cisco documentation CD is available in the lab room, but the exam assumes knowledge of the more common protocols and technologies. As of March 2006, the documentation can only be navigated using the index; the search function has been disabled. No outside reference materials are permitted in the lab room. You must report any suspected equipment issues to the proctor during the exam; adjustments cannot be made once the exam is over.

Lab Exam Grading
Each question on the lab has specific criterion. The labs are graded by proctors who ensure all the criterion are met and points are awarded accordingly. The proctors use automatic tools to gather information from the routers to perform some preliminary evaluations, but the final determination of a correct or incorrect configuration is done by a trained proctor.

Results
You can review your lab exam results online (login required), usually within 48 hours. Results are Pass/Fail and failing score reports indicate major topic areas where additional study and preparation may be useful.

Reevaluation of Lab Results
You may request a reevaluation of results for Routing and Switching, Security and Service Provider labs for up to 14 days following your exam date. Use the link next to your lab record called "Request for Reread". Due to the equipment used, rereads are not available for the Voice and Storage Networking exams. Each reread costs US$250 plus any applicable local taxes. Payment is made online via credit card and your card will be charged upon receipt of the request. You may not cancel the reread request once the process has been initiated and refunds are only given when the results change from Fail to Pass.

A reread consists of a second proctor loading your configurations onto a rack to recreate the test and rescore the entire exam. This process may take up to three weeks after receipt of payment. Only one reread per lab attempt is permitted. The result of the reread is an updated score report with success rates for each major section. Be aware that scores may decrease. Exams receive a Pass mark only when the total exam score exceeds 80%. Before requesting a reread, consider that, historically, only 0.3% of exams have been changed from Fail to Pass.

Best of luck to you!

Oh, and I have a coworker who just passed his NA. Said the config register stuff wasn't even on there, but if it was, it wouldn't be as detailed as I was thinking.

beatbox32 · 08-01-2007, 04:16 PM

Yeah, I'll be taking the lab in San Jose. It's about a 5 hour drive from me. I definitely have been without a life for awhile, but the more I read and re-read and do things in the lab, the more the stuff becomes second nature.

If you haven't heard of it already, there's a sweet little app that will load IOS on your PC, called Dynamips. Follow this link to Dynagen which is a front-end for Dynamips. http://dynagen.org/ This thing has been a real lifesaver (and wallet saver) for me while studying.

gwilks98 · 08-03-2007, 10:55 PM

Quote:

Originally Posted by beatbox32

Yeah, I'll be taking the lab in San Jose. It's about a 5 hour drive from me. I definitely have been without a life for awhile, but the more I read and re-read and do things in the lab, the more the stuff becomes second nature.

If you haven't heard of it already, there's a sweet little app that will load IOS on your PC, called Dynamips. Follow this link to Dynagen which is a front-end for Dynamips. http://dynagen.org/ This thing has been a real lifesaver (and wallet saver) for me while studying.

Thanks,...I need all the help I can get. We recently put a Mars system in place and I got a stack 5 inches high of false positives to go through. Half that crap is difficult to determine the difference between the real fix and one that will bring down half the company.

gwilks98 · 11-01-2007, 02:19 PM

DAMMIT.

Took my CCNA today. Got an 847/1000, passing score is 849. Can't retake for 6 days, the exam changes in 5 with new updated material.

Get to go get more study material and try again in hopefully november.

I hope you do better on your CCIE. It sucks to miss it by 1 question!

beatbox32 · 11-06-2007, 08:40 AM

Ugh! That's the worst. Funny, the same thing happened to me the first time I took my CCNA. Missed it by just a few points. But I rescheduled for a week later and passed. Though you have it much rougher, with the new material and all. But at least you got to experience the way Cisco does there testing and kind of know what to expect. I'm sure you'll ace it the second time around.

I'm still scheduled for my CCIE lab on the 7th of January, so wish me luck!

gwilks98 · 11-07-2007, 10:11 PM

best of luck man. I can't imagine how big of a pain that thing is.

Kevster · 11-07-2007, 11:53 PM

Quote:

Originally Posted by beatbox32

Ugh! That's the worst. Funny, the same thing happened to me the first time I took my CCNA. Missed it by just a few points. But I rescheduled for a week later and passed. Though you have it much rougher, with the new material and all. But at least you got to experience the way Cisco does there testing and kind of know what to expect. I'm sure you'll ace it the second time around.

I'm still scheduled for my CCIE lab on the 7th of January, so wish me luck!

I used to work with six CCIEs at my old company, as we were a big cisco customer. My CCNA experience was similar the first time I took it, and I passed it a week later.

Have you already taken the written portion and you are now just ready for your lab exam? My last co-worker who took the lab had to take it three times before he passed it.

I'm not in any hurry to take it right now, as the company I work for now is primarily Juniper-based. Needless to say, I'm working on my JNCIS.

gwilks98 · 06-25-2008, 09:24 AM

Quote:

Originally Posted by gwilks98

DAMMIT.

Took my CCNA today. Got an 847/1000, passing score is 849. Can't retake for 6 days, the exam changes in 5 with new updated material.

Get to go get more study material and try again in hopefully november.

I hope you do better on your CCIE. It sucks to miss it by 1 question!

Well, I'm at the Cisco Networkers conference in Orlando and decided to retake my CCNA. I passed this time with an 854. (Keep in mind, I was only able to study last week, as my father was in the hospital for a month and a half prior to that.)
I'm a little pissed though. Not only was the exam easier (fewer subnetting calculations on the average question), but they lowered the passing score to 825, so I would have passed last time had they done that then. Grrrrr....

Oh well, I'm a CCNA now. I guess that means I can be fired for screwing up now since the cert says I should know better.

CCNP? I guess that's next for me.

Prngr44 · 06-25-2008, 11:11 AM

Congrats!

06-25-2008, 11:11 AM	#15
Prngr44 Rear Admiral Lower Half Join Date: Feb 2003 Location: St. Louis Posts: 2,620	Congrats! __________________ http://otthouse.blogspot.com

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07-27-2007, 09:04 PM	#3
gwilks98 Vice Admiral Join Date: Aug 2000 Location: StL Posts: 4,300	Cool...I've already got that down. I was just worried they were concerned with memorizing the other more obscure bit placements. I know someone who passed their CCIE. He said it was the worst 2 years of studying of his life. Good luck to you.

07-28-2007, 08:21 AM	#4
beatbox32 Lieutenant Junior Grade Join Date: Feb 2005 Location: Orange County, CA, USA Posts: 159	Thanks! I've definitely been without a life for the past year and a half. I'm scheduled to take the lab in January. When are you going to sit for the CCNA? Best of luck to you my friend! Let us know how it goes.

08-01-2007, 04:16 PM	#8
beatbox32 Lieutenant Junior Grade Join Date: Feb 2005 Location: Orange County, CA, USA Posts: 159	Yeah, I'll be taking the lab in San Jose. It's about a 5 hour drive from me. I definitely have been without a life for awhile, but the more I read and re-read and do things in the lab, the more the stuff becomes second nature. If you haven't heard of it already, there's a sweet little app that will load IOS on your PC, called Dynamips. Follow this link to Dynagen which is a front-end for Dynamips. http://dynagen.org/ This thing has been a real lifesaver (and wallet saver) for me while studying.

11-01-2007, 02:19 PM	#10
gwilks98 Vice Admiral Join Date: Aug 2000 Location: StL Posts: 4,300	DAMMIT. Took my CCNA today. Got an 847/1000, passing score is 849. Can't retake for 6 days, the exam changes in 5 with new updated material. Get to go get more study material and try again in hopefully november. I hope you do better on your CCIE. It sucks to miss it by 1 question!

11-06-2007, 08:40 AM	#11
beatbox32 Lieutenant Junior Grade Join Date: Feb 2005 Location: Orange County, CA, USA Posts: 159	Ugh! That's the worst. Funny, the same thing happened to me the first time I took my CCNA. Missed it by just a few points. But I rescheduled for a week later and passed. Though you have it much rougher, with the new material and all. But at least you got to experience the way Cisco does there testing and kind of know what to expect. I'm sure you'll ace it the second time around. I'm still scheduled for my CCIE lab on the 7th of January, so wish me luck!

11-07-2007, 10:11 PM	#12
gwilks98 Vice Admiral Join Date: Aug 2000 Location: StL Posts: 4,300	best of luck man. I can't imagine how big of a pain that thing is.

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