Subnet address exercise

[Marlboro]

Hello all,
I'm currently taking CCNA I course.
There's an exercise that I got stuck on question 7, 8, 9, 10, 11
It has answered but I don't understand on how it works. This is a lecture exercise.

Problem:
Your company has been assigned the following IP address: 192.112.136.0 /27
Your group has been assigned the fourth subnet.

What is the "your group has been assigned the fourth subnet" mean in this case?

1. What class is this address?
class C

2. What is the default address format?
11111111.11111111.11111111.00000000

3. What is the default subnet mask for this address?
255.255.255.0

4. What is the actual subnet mask for this address?
255.255.255.224

5. How many useable subnets are available for assignment?
6

6. How many useable hosts per subnet are available for assignment?
30

7. What is the network address for your subnet?
( 199.112.136.128 )

8. What is the broadcast address for your subnet?
( 199.112.136.159 )

9. What is the range of the available hosts for your subnet that you are able to assign?
( 199.112.136.129 to 199.112.136.158 )

10. What address will be assigned to the router for your network?
( 199.112.136.129 )

11. What is the range of the available hosts that you can actually assign to PCs on your network?
( 199.112.136.130 to 199.112.136.158 )

Please help, Thanks much.

[jjbrog]

I don't know where they get 199.112.136.128 from aside from it being the 5th network.
but the rest would be accurate the incrementing bit is 32(think 256 - the 224 in the mask)

so youre networks would be
1.0(1-30 31 is broadcast)
2.32(33-62 63 is bc)
3.64(65- 94 95 is bc)
4.96(97-126 127 is bc)<----4th subnet
5.128
6.160
7.192
8.224


and yes generally the first host address would go to the default gateway
aka router

the answers their telling you don't quite add up to me. their correct for the subnet their telling you, but its the 5th not the forth.

and for question 5 its 8 not 6.

I haven't studied subnetting fully in a wile, but I'm pretty sure I'm rigth on this though.

[RouteThisWay]

192.112.136.0 /27

The fourth subnet would be:

192.112.136.96 (subnet)
192.112.136.97-126 (hosts)
192.112.136.127 (bc)

That should help you get started, as what JJ posted.

Not sure where the 199 comes in.

[jjbrog]

I think there was a typo in there, I assume 199 is ment to be 192 since the rest of its the same, sounds like the question system might be kinda screwy.

In my last ccna class we had several questions that were like one asked "what is NOT a default setting on a serial interface" A. encapsulation hdlc B.shutdown C. no ip address D.clock rate 56000

I answered D, and was wrong. I don't know what they wanted me to answer though, but the teacher fixed it.

[johnwest43]

If the no ip zero subnet command is used then .128 is the 4th subnet and because of that there are only 6 subnets not 8. Hope this helps.

[RouteThisWay]

Originally Posted by johnwest43

If the no ip zero subnet command is used then .128 is the 4th subnet and because of that there are only 6 subnets not 8. Hope this helps.

That would be handy to have been specified in the scenario, considering that ip zubnet-zero is enabled by default these days.

I am aware this wasn't the case a number of years ago, and CCNA practice tests would trip people up by assuming the test-taker knew that ip subnet-zero is disabled by default, thus leaving you with 2 less subnets.

So perhaps the op's CCNA course is teaching to old material?

[Marlboro]

I'm apologize for the mistype, the IP address should be 199.112.136.0 /27

If .128 is the 4th subnet, how do you get this number?
_______________________________
1.0(1-30 31 is broadcast)
2.32(33-62 63 is bc)
3.64(65- 94 95 is bc)
4.96(97-126 127 is bc)<----4th subnet
5.128
6.160
7.192
8.224

Is this a default table from somewhere? and does the increment always by 32 because of the ip address?
This is my first networking course, I really want to understand more into it.
Thank you for all the help.

[jjbrog]

I assumed your scenario was around the idea you can use subnet zero but it is correct if not.

with subnet zero disabled that would make the 128 the 4th one, like John mentioned.

The 32 comes from the subnet mask, theres a really good tutorial on all that somewhere on this board I'll see if i can find it for ya

[jjbrog]

Subnetting Made Easy

also once you get a good hold on it subnettingquestions.com - Free Subnetting Questions and Answers Randomly Generated Online has a bunch of questions you can try to answer, practice on that will help.

You need to be good and fast as possible cause the from my understanding its vitle to passing the exams. Not the class room exams, but the real cert exams. you'll also need to learn how to subnet a address down using different masks depending on how many hosts you need. Starting with the largest number of hosts first, all the way down to router to router serial connections which only need two addresses thus a /30. Also for needing to configure eigrp/ospf and access lists you'll need to know wildcard masks, which is essentially a subnet mask in reverse.

start with class C as thats easy as cake when ya figure it out.

what are the titles of the ccna classes your taking? it was mentioned it could be older material based on when subnet zero was disabled by default which is not the case in newer IOS so i imagine your using the older 801 exam material? I asked because thats the case with me, we had a chapter on igrp for example, which doesn't exist at all on newer ios, so we skipped it and the teacher made his own presentation on eigrp instaid.

Trust me at first glance this is a very confusing topic, especially with those that suck at math like myself.

And your question about charts, yeah there are some, their good to look at for reference, but you really need to know how to do this without memorizing a chart.

But its not bad, 6 months ago a ip address was just a number to me and nothing more, I really had no idea, I came into learning networking knowing literally nothing, the first day the teacher was teaching it, I was beyond lost

[mikej412]

Originally Posted by jjbrog

theres a really good tutorial on all that somewhere on this board I'll see if i can find it for ya

This one?
Subnetting Made Easy

[Marlboro]

/sigh
Thanks alot guys for the help and info, I'm getting it now I need to do more practice for subnetting.

btw, the course is CCNA I, Network Fundamentals

Thanks again.

[jjbrog]

no prob, is routers and routing basics up next by any chance? if so its definitely the old material.

[Marlboro]

Yes, the second course is gonna cover router material.

[gmeyer]

You need to be good and fast as possible cause the from my understanding its vitle to passing the exams.

Your understanding is correct. Without going into too much detail, don't expect something like 'here's an IP and mask, now subnet into x smaller networks'. That would be too straight forward. Rather, expect to have a problem where subnetting is a small portion of the overall problem.

you'll also need to learn how to subnet a address down using different masks depending on how many hosts you need. Starting with the largest number of hosts first, all the way down to router to router serial connections which only need two addresses thus a /30.

These are easily spotted, and most practice materials (I.e., books by Todd Lammle or Odom) will have these questions to help you along.

Trust me at first glance this is a very confusing topic, especially with those that suck at math like myself.

It is confusing, if you have never been exposed to it before (and most of us haven't until we start studying for the exam). The trick is to learn, then practice. I would definitely recommend chapter 3 of Todd Lammle's CCNA study guide. It covers the topic in a way that's more like how people think & solve problems (as opposed to cisco methods that revolve more around binary math which is much too slow to do on the exam). I would also recommend (once you have gone through chapter 3 of Lammle a few times), www.subnetskillz.com. It's a good place to practice with random questions/answers, and explanations of the answer if you get it incorrect.

And your question about charts, yeah there are some, their good to look at for reference, but you really need to know how to do this without memorizing a chart.

Some charts have value, some are just too big. I personally used a small chart to get me through the CCNA. The problem with charts is that there are so many that are adapted to so many different ways of thinking/problem solving, it's generally best to figure out a process that works for you, is quick, then develop your own chart.

[GiddyG]

I think someone on here mentioned www.subnettingquestions.com too. I go on and do a few questions a day. Keeps you thinking.