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TOPIC: So you think you know your routers eh ?

So you think you know your routers eh ? 12 years 11 months ago #1406

  • sahirh
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Well I'm busy studying for my recertification.. and I'm having to go through material that I haven't seen in quite a while (I still have never gone near a Novell network). So I thought I'd throw you a couple of questions about cisco routers.. see if you can answer them without hitting google :

1. How many bits are there in the configuration register and what do bits 0-3, 6, 8 and 13 do ?

2. If I'm at a prompt that says > and I type o/r 0x2142 what would I be doing ?

3. If I get some sessions listed after typing show sessions what will happen if I press <enter> twice at the command line ?

4. What would the command clear line 3 do ?

5. In the middle of a telnet session if I press ctrl+shift+6+X, what will happen ?

There those weren't so hard were they ? If you got them right, maybe we can throw a few harder ones at you :)

Cheers,

btw I'm not posting the answers because I'm sure everyone who knows them will be crowing in their own posts.. I vote that Chris and Tom will answer correct first. I'm 'routing' for you guys -- yeah I know thats a bad joke ! :P
Sahir Hidayatullah.
Firewall.cx Staff - Associate Editor & Security Advisor
tftfotw.blogspot.com
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Re: So you think you know your routers eh ? 12 years 11 months ago #1412

  • tfs
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Ok,

1) 16 bits (since we use number such as 2142). Now if I know what the bits are for (and I have not been studying for the CCNA test), I'd need to get a life.

2) changes config register to something

4) drops line 3

Now, I'll leave the other for someone else.
Thanks,

Tom
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Re: So you think you know your routers eh ? 12 years 11 months ago #1413

  • sahirh
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Not bad Tom :)

1. Correct ! Though knowing what some of the bits do is important if you need to troubleshoot.

2. Correct ! Changes config register to 2412 when you break the boot sequence on 2500 series routers.. its different for 2600.

3. Correct ! Drops whoever is connected to the router as line 3.

So part 2 of question 1 is still left.. as are 3 and 5.
Sahir Hidayatullah.
Firewall.cx Staff - Associate Editor & Security Advisor
tftfotw.blogspot.com
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Re: So you think you know your routers eh ? 12 years 11 months ago #1414

  • Chris
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Well I will most certainly not finish it all up since I have no clue about the 2nd part of the 1st question.

I think tom's note on that is one that I must agree on aswell :)

Coming to No3, I really can't remember, but if I was to guess, I'd say that hitting enter twice will connect you to the first available session ?

As for question 5, it will allow you to detach from a session, dropping you back into the CLI prompt;

How did I go ?
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
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Re: So you think you know your routers eh ? 12 years 11 months ago #1415

  • sahirh
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Not bad at all :)

You're right, pressing enter twice will take you back to the last telnet session you were at when you suspended it


And pressing ctrl+alt+6 and then X will suspend a telnet session.

As for the configuration register.. well bit 6 is the most important.. when its set, you tell the router to disregard the config in NVRAM, you use this when you have forgotten the password.

Bits 0-3 are the 'boot bits' 00 tells it to boot into rommon mode (> prompt), bit 01 tells it to boot an IOS image from ROM, and 02 - 0F tells it to boot from what is saved in NVRAM.

Bit 8 disables break.

:)

I think I got em all right
Sahir Hidayatullah.
Firewall.cx Staff - Associate Editor & Security Advisor
tftfotw.blogspot.com
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Re: So you think you know your routers eh ? 12 years 11 months ago #1416

  • tfs
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The question is do you know them for the exam?

I don't need to know the bits, normally, that's what I have manuals for. Even if I did, I would check first anyway, as I wouldn't want to screw it up.
Thanks,

Tom
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