IP Addressing Scheme - Confusing...

There's some bad maths up there...

Class A = 1 - 126.
Private range 10.0.0.0 - 10.255.255.255.
16,777,314 (2^24 - 2) hosts per network.
126 networks possible in the clasful range.

Class B = 128 - 191.
Private range 172.16.0.0 - 172.31.255.255.
65,534 (2^16 - 2) hosts per network.
4,128,768 networks available [191 - 128 = 63] (63 x 256 x 256) in the classful range.

Class C = 192 - 223.
Private range 192.168.0.0 - 192.168.255.255.
254 (2^8 - 2) hosts per network.
2,031,616 networks available [223 - 192 = 31] (31 x 256 x 256) in the classful range.

Class D = 224 - 239.
Reserved for multicasting.

Classs E = 240 - 255
Reserved by the IANA.



If you're going for a CCNA, you should know these numbers and their classful ranges and subnet masks without having to think. If these numbers aren't second nature to you now, then you need to study some more before heading off to a CCNA course.

As far as using 2 to the powers of for subnetting, it's a nice skill to have, but *totally* un-necessary as a way of calculating subnetting, especially if you want to do it in your head, quickly. Unless you have learned all the 2 to the powers of numbers of course. I only know my 2^8, 2^16 and 2^24 numbers. The rest can be done with simple maths and some very minor times-table type multiplication. Looking at binary is better when we are talking about summarisation, but again there is an easy way round that which makes summarisations really easy too .

Hey BCStorm where is the bad maths coming from?

The Book? or the replies?

hey talk2sp I will be in kaduna during chrismass and we will discuss subnetting in details from the magic number concept to VLSM up to route summarization and wild card mask. there is a trick you need to know and once you get it you can play around with subnetting the way you use to play around with women in skul... hahhahah

have a super weeeeek

see ya soon

Sose.............................................eeeee. Man u are em telling everyone the P3t3r of then. Admin take this post out (Lol, LMAO). Aight Sose i will be in FCT for the Hols. Will meet u up @ Kaduna. Thanks man,..... Don't worry i wont say to the house wat u use to do back then @ School? I can cover u up u knw... lol



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Hey BCStorm where is the bad maths coming from?

The Book? or the replies?

Dunno, but...

Please explain this:
Class A 1.0.0.0 through 127.0.0.0. the network number is contained in the first octet. this class provides for a 24 - bit host part allowing roughly 1.6million host per network

Class B 128.0.0.0 through 191.255.0.0. the network number is in the first 2octets. this class allows for 16, 320 nets with 65, 024 hosts each

Neither is correct. Your class A hosts are out by a magnitude of 10, your class B hosts out by 510. and your network count is several million short.
I'm not criticing, but I am surprised that nobody pointed out these fundamental errors before now. I don't know if the maths is yours or from the books you have. Either way they need correcting so that you can proceed from the right starting point.

BCStorm well i thought u should have pin pointed the errors. well i will go over it again and reply thy.

thanks


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