POP quiz!!!

Selfmade

PM ME YOUR ANSWERS!!!


1. There are 2 routers, they have a serial link between them, the clock rate is configured correctly, the cables are good, and the router ports work, yet these 2 routers cannot communicate. OSPF is configured on the router, The interface IP addressing is correct on both ends. What are 4 reasons (5 if you're good, and one answer can be split in 2 for the 5 answer total) that these 2 routers cannot communicate?

2. What command prevents routing updates from being sent out of a ACTIVE interface?

3. EIGRP is configured on 2 routers, almost everything is configured correctly, yet the link state shows an adjacency one minute, then the adjacency goes down for a few seconds, then comes back up. This process repeats itself, what causes this?

4. There are 3 switches, they are all in transparent mode, VLANs are set up on each switch, trunk links are configured correctly, STP is enabled, yet there is a broadcast storm going on, what could possibly cause this?

5. Inter-VLAN routing is set up on a router, the subinterfaces are given correct IP addresses, the main interface has no shutdown on it, yet none of the subinterfaces are functioning correctly, why would this happen?


PM ME YOUR ANSWERS!!!

Let's have some fun here folks, if you have any questions you can post the in the thread, however, ONLY PM me your answers!!!

Selfmade

corrected question #2, meant to say ACTIVE instead of specific, sorry for that error folks

These questions are ambiguous on purpose, that doesn't mean that every answer you come up with will be wrong. For most of these, there are several reasons, if you list a few, then you'll probably be right. So with that in mind, do your best!! This should help some people wanting to test their knowledge beyond the "memorization"

thenjduke

I finish my CCNA yesterday. No more thinking about this for now

Selfmade

thenjduke wrote: »

I finish my CCNA yesterday. No more thinking about this for now

congratulations!!!

but do it for the fun and challenge

thenjduke

Well I tried three... Hope I got at least one right

Selfmade

thenjduke wrote: »

Well I tried three... Hope I got at least one right

I give you credit for all 3, even though you only really partially answered the 4th one, that was still a very good answer.

Remember, the rest of you, when I say something is configured, that does NOT mean it was configured correctly, unless i specifically say it is configured correctly.

Nothing is true, everything is permitted

alan2308

First attempt PM'ed.

Selfmade

alan2308 wrote: »

First attempt PM'ed.

Ok, you got 2 right, to clarify

1. the cables work fine, there are NO faults on the cable or on the router port. PPP and encapsulation, usernames, and whatnot, have NOTHING to do with this problem, this problem hinges solely on how OSPF is configured. Only OSPF configuration and addressing answers will be correct. I did not say that OSPF was configured correctly.

2. This is an easy question basically the gimme

3. This question, I'll give a hint, one of the answers from OSPF applies here, only it's configured incorrectly. The question is what can you configure to bring up a link and yet kill it several moments later?

4. I've gotten several different answers, but not quite the one i'm looking for, so here's your clue, it hinges on the VLANs, and doing a show vlan brief on all 3 switches would reveal the answer (yeah what a big hint)

5. This is a pretty easy one, there's at least 2 answers to this problem you don't have to give both, one is easy to figure out, the other requires you to believe that an administrator is dumb enough to do that on a subinterface.

alan2308

Ok, on question 1 I took it to mean ALL communication between the two routers failed (pings included), not just OSPF. I guess that does change things a bit.

And my answer for #4 would cause it if there are redundant links. I'm assuming there are?


//wanders off grumbling about technicalities.

Selfmade

yes, there can be redunant links

imagine 3 switches, the topology is like a triange

SW1

SW2 SW3

but the topology isn't the point, it has nothing absolutely nothing to do with the answer

Selfmade

Notgoing2fail has come really close to answering all 5 questions correctly, he's only a little off on numbers 3 and 4!

notgoing2fail

Selfmade wrote: »

Notgoing2fail has come really close to answering all 5 questions correctly, he's only a little off on numbers 3 and 4!

Yeah these pop quizzes are really good. There's one going on in the CCIE forum and I think it's a good idea to have these for CCNA as well....

Keeps everyone on their toes....

spartangtr

These should be like a weekly thing. With the answers posted at the end of the week.

Selfmade

i'm game enough to post quizzes, but others can help develop quizzes

hopefully there's enough interest in this

they don't have to be the hardest questions

some really good basic questions can help people in their studies

thenjduke

Selfmade wrote: »

i'm game enough to post quizzes, but others can help develop quizzes

hopefully there's enough interest in this

they don't have to be the hardest questions

some really good basic questions can help people in their studies

Selfmade like I said to you last night these do challegene us. I am willing to answer more. I am actually working on number like you told me last night. Thanks for all the help man.

chmorin

It would be more clear if it were visio'd up or screenshooted somewhere of what topology we are actually dealing with.

Selfmade

you don't need the topology to answer any of the questions

they are all plainly written as possible all you're dealing with is parameters and specific situations

alan2308

Selfmade wrote: »

1. the cables work fine, there are NO faults on the cable or on the router port. PPP and encapsulation, usernames, and whatnot, have NOTHING to do with this problem, this problem hinges solely on how OSPF is configured. Only OSPF configuration and addressing answers will be correct. I did not say that OSPF was configured correctly.

Here's where I disagree with question one. Based on this, these two routers CAN communicate and what you're looking for is why they can't form an OSPF adjacency. To put it another way, the routers can communicate, the OSPF processes can't.

I know this is a nit-pick, but everything that I've ever been told about Cisco questions is to not read more into the question than what's there. And it says twice in the question that the routers can't communicate.

thenjduke

alan2308 wrote: »

Here's where I disagree with question one. Based on this, these two routers CAN communicate and what you're looking for is why they can't form an OSPF adjacency. To put it another way, the routers can communicate, the OSPF processes can't.

I know this is a nit-pick, but everything that I've ever been told about Cisco questions is to not read more into the question than what's there. And it says twice in the question that the routers can't communicate.

There are 2 routers, they have a serial link between them, the clock rate is configured correctly, the cables are good, and the router ports work, yet these 2 routers cannot communicate. OSPF is configured on the router, The interface IP addressing is correct on both ends. What are 4 reasons (5 if you're good, and one answer can be split in 2 for the 5 answer total) that these 2 routers cannot communicate?

Here is my problem with this question. The question states they have a serial link between them and the cables are good and the router ports work and the clock rate is configured and then states they can not communicate. (What does it mean they can not communicate.) This leads me to believe the routers are not power on or the cabling for the DCE is not configure on the right router. I was wrong on both of these answers so I am still looking into it. (My other question is now since OSPF is configure on one router in the question this means that the neighbor relationship may have not form because the other router does not have the OSPF configure on it.)

alan2308

I also want to make sure that you don't take any of this the wrong way Selfmade. I am in no way attacking you, I'm just putting WAY too much effort into defending my answers.

I still believe that I gave you 5 perfectly valid answers.

thenjduke

alan2308 wrote: »

I also want to make sure that you don't take any of this the wrong way Selfmade. I am in no way attacking you, I'm just putting WAY too much effort into defending my answers.

I still believe that I gave you 5 perfectly valid answers.

I did not take it as you attacking him at all.

notgoing2fail

Well I think the more we do these kinds of quizzes the better we all get at asking the "right" questions whether as the contestant or host.


When you know the answer and are asking the question, I think it's hard to phrase it in a way where you don't know the answer...? Does that make sense?


I see none of this at nitpicking, I see these as good questions that can lead all of us who participate to be better engineers....

thenjduke

notgoing2fail wrote: »

Well I think the more we do these kinds of quizzes the better we all get at asking the "right" questions whether as the contestant or host.


When you know the answer and are asking the question, I think it's hard to phrase it in a way where you don't know the answer...? Does that make sense?


I see none of this at nitpicking, I see these as good questions that can lead all of us who participate to be better engineers....

Exactly my thought too. I feel it helps us to be better at troubleshooting problems. It is good to keep our minds going this way we know our material and make us better out there for this poor excuse of a economy.

notgoing2fail

thenjduke wrote: »

Exactly my thought too. I feel it helps us to be better at troubleshooting problems. It is good to keep our minds going this way we know our material and make us better out there for this poor excuse of a economy.

So true....


Plus, as we all continue our certs, we begin to forget the minor details of previous topics. It's extremely difficult to stay sharp in all areas unless you're some kind of savant....

Selfmade

what's really sad is that only a few attempted the quiz.

yes, I could word things a little better

i can write questions that look pretty exam worthy if I really want to, there isn't really much you can't take out of the books or out of any study guide available or from the NetAcad that won't have a similiar sounding question on the actual exam i'd imagine.

alan2308

Selfmade wrote: »

what's really sad is that only a few attempted the quiz.

yes, I could word things a little better

i can write questions that look pretty exam worthy if I really want to, there isn't really much you can't take out of the books or out of any study guide available or from the NetAcad that won't have a similiar sounding question on the actual exam i'd imagine.

Well, you did put it up on a Friday night. Unlike the 4 of us, I'm sure a lot of people do have a life.

JockVSJock

At this stage for my CCNA, most of these questions are over my head. Would be great if you eventually posted the answers.

BTW, this is a good idea.

chmorin

These are a very good idea, I think we just need a better way to present them.

Selfmade

Ok, here's my answers

1. There are 2 routers, they have a serial link between them, the clock rate is configured correctly, the cables are good, and the router ports work, yet these 2 routers cannot communicate. OSPF is configured on the router, The interface IP addressing is correct on both ends. What are 4 reasons (5 if you're good, and one answer can be split in 2 for the 5 answer total) that these 2 routers cannot communicate?
Two routers may not form an OSPF adjacency if:

The subnet masks do not match, causing the routers to be on separate networks.
OSPF Hello Timers do not match
OSPF Dead Timers do not match.
OSPF Network Types do not match.
There is a missing or incorrect OSPF network command.

2. What command prevents routing updates from being sent out of a ACTIVE interface?

passive-interface command

3. EIGRP is configured on 2 routers, almost everything is configured correctly, yet the link state shows an adjacency one minute, then the adjacency goes down for a few seconds, then comes back up. This process repeats itself, what causes this?

If you change the hello interval, make sure that you also change the hold time to a value equal to or greater than the hello interval. Otherwise, neighbor adjacency will go down after the hold time expires and before the next hello interval.

A lot of people mentioned the link flapping, that IS true . . . . my question was a little bit beyond the obvious, still a valid answer though

4. There are 3 switches, they are all in transparent mode, VLANs are set up on each switch, trunk links are configured correctly, STP is enabled, yet there is a broadcast storm going on, what could possibly cause this?

All switches have VLANs setup on them, but one switch is missing a vlan that is present on the other 2 switches, this can cause a broadcast storm.

5. Inter-VLAN routing is set up on a router, the subinterfaces are given correct IP addresses, the main interface has no shutdown on it, yet none of the subinterfaces are functioning correctly, why would this happen?

Incorrect encapsulation type
Encapsulation not matched to correct vlan
Subinterface was shutdown by a dumb administrator


Discuss my answers, feel free to dispute them, just be civil, remember, this is just an opportunity to not just test your knowledge, but to gain it as well.

alan2308

Selfmade wrote: »

4. There are 3 switches, they are all in transparent mode, VLANs are set up on each switch, trunk links are configured correctly, STP is enabled, yet there is a broadcast storm going on, what could possibly cause this?

All switches have VLANs setup on them, but one switch is missing a vlan that is present on the other 2 switches, this can cause a broadcast storm.

This is the one that I never figured out.

Is this something that is mostly theoretical or is it common? If this is really something that is a real possibility, then this would be a real good argument in favor of VTP since there's so many good ones against VTP.

notgoing2fail

alan2308 wrote: »

This is the one that I never figured out.

Is this something that is mostly theoretical or is it common? If this is really something that is a real possibility, then this would be a real good argument in favor of VTP since there's so many good ones against VTP.

I've been meaning to lab this up and see the storm for myself....

This is a fundamental function that I and we should all know....I am pretty shocked that transparent switches work this way considering their functions...