Errors in the CCENT/CCNA ICND1 Official Exam Certification Guide, Second Edition ?

I am taking the ICND1 test next week and I have been running those a lot of the troubleshooting problems in the book. I came across a problem that made me scratch my head.

On page 494 of Odom's ICND1 book, there is the answer for Scenarion Part A. R1 has two Fastethernet interfaces; each with it's own subnet. It has been given the IP address of 10.10.24 /21. It claims to have the subnet of 10.10.24.0 /21. I'll buy that, it looks legit. However, my problem is with a PC is also suppose to be in the subnet. It has an IP address of 10.10.23.11 /21. To me it looks like it's in a completely different subnet and there is no mention of VLANs in the scenario:
00011/000 - 24
00010/111 - 23
(these are the numbers from Octet 3 where the subnet divides the network and host bits.)
Am I missing something here? The book makes no mention of this at all.

Also from R1, the other Fastethernet interface has an IP address in the middle of the subnet range. This router should be the default gateway. Isn't always assumed that the router interface should be the next address/number to come after subnet address?
IP address - 10.10.15.1 /21
Subnet - 10.10.8.0 /21

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Comments

MosGuy

I'm not seeing the error you're describing. R1 has an address of: 10.10.24.1 & PC11 has the address: 10.10.25.1. Since it's a /21 the block size is 8. Therefore the range is 24-31. The diagram looks correct to me. Regarding your question about the default gateway and IPs. While many do assign either the first (or last) usable IP addresses to routers. It's not a firm rule. As long as the router is within the same subnet, it can be assigned any IP. So an address in the middle is perfectly valid.

SpencerClark

We may be looking at different versions of the book. PC11 has an address of 10.10.23.11 /21, not 10.10.25.11. (I double checked to make sure.) If the address was the latter, then yes I would agree.

However, the more I look at this problem, I think that there is an error.

j-man

I think you have a different printing. Mine also shows PC 11 as 10.10.25.1/21 in both Figure 15-5 (pg 492) and Figure 15-6 (pg 494)

michaelcox

I have 13th edition (February 2011) and it shows PC 11 having IP 10.10.25.1 /21.

SpencerClark

I guess they must have fixed it since then. I have the fifth edition. Here is screenshot just to show that i'm not crazy.

MosGuy

SpencerClark wrote: »

I guess they must have fixed it since then. I have the fifth edition. Here is screenshot just to show that i'm not crazy.

That's interesting, I checked both my hard paper back & e-book kindle edition. The kindle is the 5th printing but shows the IP "10.10.25.1". The hard copy is 6th printing with "x.25.1". It seems they corrected it partway through the fifth edition, or at least on the e-book and in paper with the sixth. If you haven't already done so, I would suggest scanning the official book errata. To see what other errors you may come across.

hiddenknight821

SpencerClark wrote: »

I guess they must have fixed it since then. I have the fifth edition. Here is screenshot just to show that i'm not crazy.

Holy smoke! I have the fifth printing of the 2nd Edition hard-cover book as well, which was published in October 2008. Now I know you are not crazy!

Because I just saw a mistake (dunno if mine or yours is a mistake). On the upper-right part of the network you posted, the subnet I had was 192.168.4.16/28. Not 192.168.4.21/24. No kidding. I just found out that the PDF version was the same as yours. If you guys are curious to know, I can come back later to take a snapshot of the hard-copy.

SpencerClark

The picture I posted is from the PDF. This problem has provided more teaching and understanding of networking that it originally intended.

It has shown this forum is a great place to go when you have a question.

Thanks again for all of your help!