Mistakes in Lammle's book? Written Lab 5 VLSM

So I was doing my studies and came across 2 problems I take issue with or maybe I just don't understand fully.

The instructions are as follows:

For each of the following sets of networks, determine the summary address and the mask to be used that will summarize the subsets.

192.168.1.0 through 192.168.120.0
172.16.1.0 through 172.16.7.0

Please let me know the answers and I'll compare them to the book and see if they are the same.

If this violates any copyright laws, please let me know any I'll take this down. The use is for educational purposes and not a means to sell information.

Thanks

SG

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Comments

TehToG

1) 192.168.1.0 through 192.168.12.0 - Assuming the book and not what you've written

192.168.1.0/20 was my penciled in answer and I believe that to be right.

2) 172.16.1.0 through 172.16.7.0

172.16.1.0/21

To be honest, Most of us own the book in question. If you want to understand the answers then tell us;
1) The question
2) Your answer
3) How you got to that answer.

Then we can help.

Sounds Good

I'm looking at number 6 for the first question. Unless it's a typo, it's

6) 192.168.1.0-192.168.120.0
My answer - 192.168.0.0 /16
Their answer - 192.168.0.0 /25

Reasoning. Block is 128 on the 3rd byte so it's part of the 192.168.0.1 - 192.168.127.254 host range

7) 172.16.1.0 through 172.16.7.0
My answer - 172.16.0.0 /21
Their answer - 172.16.1.0 /21
Reasoning is right, but why do they use the 1.0 as opposed to 0.0?

In another question, it was 172.16.10.0-172.16.63.0 and the answer was 172.16.0.0 /18

Why did they choose not to include the 10.0 in the final answer, but in the previous one they included the 1.0?

Thanks for help

Sounds Good

if we AND these networks?

Thanks, but please explain your answer as just telling me the answer isn't going to do anything

Also, you didn't address the question of 172.16.10.0-172.16.63.0 summarizing to 172.16.0.0 /18

Ltat42a

Check out the errata page for this book here -

Wiley: CCNA Cisco Certified Network Associate Study Guide, 7th Edition - Todd Lammle

Sounds Good

Ahh yes, it makes sense now. My suspicions were correct.

@fahdil, if you're studying for the CCENT/CCNA, i'd suggest you look over your notes again as everything you posted was incorrect along with the reasoning.

@tehtog, you're answer for 172.16.1.0 was incorrect as well so you should probably look that over.

Thanks for the help guys!

TehToG

Should have been 172.16.0.0/21. If that's correct then It was a transposition error. I've got it written on my CCNA book here that thats the answer.

edit: Written as in it was my answer, Not the books answer.

fadhil

for 172.16.1.0 through 172.16.7.0
to do this question list all networks
172.16.1.0 10101100.00010000.00000001.00000000
172.16.2.0 10101100.00010000.00000010.00000000
172.16.3.0 10101100.00010000.00000011.00000000
172.16.4.0 10101100.00010000.00000100.00000000
172.16.5.0 10101100.00010000.00000101.00000000
172.16.6.0 10101100.00010000.00000110.00000000
172.16.7.0 10101100.00010000.00000111.00000000
hence to find a subnet mask.determine common bits(i bold common bits), there fore common bits are 21 then it will be /21
to get network address AND those network 10101100.00010000.00000000.00000000 which is equal to 172.16.0.0 hence the route summarization is172.16.0.0/21

TehToG

Fadhil. What are the available addresses (i.e. The Range) in these subnets:

1) 172.16.0.0 /21

2) 172.16.0.0 /20

Once you answer that you'll know why you're wrong.

edit: You said "172.16.7.0 10101100.00010000.00001001.00000000"

1001 is 9, not 7. 7 Would be 0111.

fadhil

TehToG wrote: »

Fadhil. What are the available addresses (i.e. The Range) in these subnets:

1) 172.16.0.0 /21

2) 172.16.0.0 /20

sorry my post had an error but i have already correct it.

iamme4eva

Sounds Good wrote: »

I'm looking at number 6 for the first question. Unless it's a typo, it's

6) 192.168.1.0-192.168.120.0
My answer - 192.168.0.0 /16
Their answer - 192.168.0.0 /25

Reasoning. Block is 128 on the 3rd byte so it's part of the 192.168.0.1 - 192.168.127.254 host range

My answer would be 192.168.0.0/17.

/16 would be 192.168.0.0 - 192.168.255.255 (subnet mask 255.255.0.0).
/17 would be 192.168.0.0 - 192.168.127.255 (subnet mask 255.255.128.0).
/25 would be 192.168.0.0 - 192.168.0.127 - same as the /17 but in the wrong octet, giving nowhere near the range you need.

fadhil

Sounds Good wrote: »

if we AND these networks?

Thanks, but please explain your answer as just telling me the answer isn't going to do anything

Also, you didn't address the question of 172.16.10.0-172.16.63.0 summarizing to 172.16.0.0 /18

172.16.10.0-172.16.63.0
after listing all networks, the common bits are 18 and the result of ANDing all networks is 172.16.0.0
hence summarization is 172.16.0.0/18

Sounds Good

Me again

Page 587 this time. Wasn't in the errata section.

int f0/0.2
encapsulation dot1q 2
ip address 192.168.10.46 255.255.255.240

Am I wrong or is the host IP for HostB and the VLAN 2 Default gateway not in the same subnet? Ergo not being a valid configuration?

for those without the book, HostB IP is 192.168.10.17

Thanks!

Sounds Good

bring up my post!

CheesyBread

192.168.10.46 255.255.255.240 and 192.168.10.17 255.255.255.240 are not in the same subnet. I don't have access to the book right now but if thats your question.

boredgamelad

I just pulled up the page you're talking about and yeah, Host B's IP address isn't in the same subnet as the gateway (f0/0.2). I wouldn't worry too much about it since the scenario is really only concerned with Host A. The fact that you caught the mistake should be reassuring!

Keep in mind that you may or may not run into questions like this on the CCNA exam(s). As mentioned in another thread these can often be thrown in as 'squirrels' intended to distract you or mislead you into overthinking or picking an incorrect answer.

Ltat42a

You can also check out Mr Lammle's forum where they discuss errata -
Errata and updates for my 7th edition - Lammle Forum

If you have Packet Tracer, he'll give you some bonus labs to go with the book -

Where to get Bonus material for my 7th Edition - Lammle Forum

hth

Sounds Good

boredgamelad wrote: »

I just pulled up the page you're talking about and yeah, Host B's IP address isn't in the same subnet as the gateway (f0/0.2). I wouldn't worry too much about it since the scenario is really only concerned with Host A. The fact that you caught the mistake should be reassuring!

Keep in mind that you may or may not run into questions like this on the CCNA exam(s). As mentioned in another thread these can often be thrown in as 'squirrels' intended to distract you or mislead you into overthinking or picking an incorrect answer.

cool thanks for confirming. I like to be thorough!

Ltat42a wrote: »

You can also check out Mr Lammle's forum where they discuss errata -
Errata and updates for my 7th edition - Lammle Forum

If you have Packet Tracer, he'll give you some bonus labs to go with the book -

Where to get Bonus material for my 7th Edition - Lammle Forum

hth

Yes I've already checked the errata and that is not in there.

And yes, I've already e-mail todd and he gave me the free bonus material!

Thanks