Valid IP

bbarrick

Finished my second read of Ch. 4 in Odom's 100-101 book and was trying to answer the questions at the beginning but I'm kind of stumped on one. It's asking for a Valid Class C IP address that can be assigned to a host. To me, it looks like there is two answers.

The correct answer it gives is 200.1.1.1

Another one of the choices is 223.223.223.255 which looks to me like it clearly falls within the max 223.255.255.0 range right?

I'm assuming that if I'm wrong it's the last octet .255, but I don't see the answer in the book.

bbarrick

Is the answer in the fact that a Class C can only hold 254 networks, making the maximum value of the last octet 254?

MosGuy

The correct answer would be 200.1.1.1 . While 223.223.223.255 does fall into the class C range. Remember that class C has a default mask of /24. So 233.233.233.0 is the network ID, usable host IPs: 233.1 - 233.254. 233.255 can't be used since it's the reserved broadcast address for the 233.0 network.

bbarrick

It's interesting that it even gives that as a potential answer in this chapter. The book hasn't covered any of that material yet. Thanks.

MosGuy

While I don't yet have the latest edition. The material is still in the 2007 copy: it should be under the "IP Addressing" section. If it's still fuzzy, I'd research on Google/Youtube or push ahead. It should gel as you get into routing concepts especially. As for the answers: they've been moved to the dvd only for the 2013 release.

Glad I could help clarify.

bbarrick

Yea, I'm going to keep pushing forward. It's just covering the basics right now and hasn't explained what subnet masks are so I'll revisit the question once I've read that part. The answers are on the page after the quiz, but it doesn't give a detailed reason, just the correct letter(s). I'll check the DVD and see if it elaborates any.

MosGuy

Assuming the question is identical to the older edition. Here's the answer from the back of the book:

B. 224.1.1.1 is a class D address. 223.223.223.255 is the network broadcast address
for class C network 223.223.223.0, so it cannot be assigned to a host.

I'll be ordering the new books since I like the look & revision of the new exams vs the retiring ones. I'll be able to compare the differences between editions once they arrive.