Reserved Private IP addresses

Jasiono

Reading Lammle's book here and I came across the Private IP Addresses portion.

He does a good job in explaining how to get the first octet value per class:

Class A, first octet, first bit, needs to be a 0 at all times, all other bits can be a 0 or a 1, leaving you with a range of:
0.x.x.x
...
127.x.x.x

Class B, first octet, first two bits need to be 10, the remaining 6 bits can be a 0 or 1, leaving you with a range of:
128.x.x.x
...
191.x.x.x

Class C, first octet, first three bits need to be 110, the remaining 5 bits can 1 or 0, leaving you with a range of:
192.x.x.x
...
223.x.x.x


I get that part easily, BUT, he shows a diagram in which:

Class A addresses are:
10.0.0.0 through 10.255.255.255

Class B addresses are:
172.16.0.0 through 172.31.255.255

Class C addresses are:
192.168.0.0 through 192.168.255.255


Questions:
Where is the 16 coming from in the class B address range, and where is the 31 coming from the class B address range?
Where is the 168 coming from in the class C address range for both starting and ending numbers in the range?

Considering class C is N.N.N.H, I can have a network of 192.168.2.x and have 254 addresses within it, correct? 192.168.2.0 being the network address and 192.168.2.255 being the broadcast address? Leaving me with the range of usable addresses to be 192.168.2.1 - 192.168.2.254


This is leading up to another question, I just want to try and find it myself, but I can't get my head wrapped around this one.

Syntax_ninja*

Within the 3 different class ranges there are ranges of set aside private IP addresses. In class A it's 10.0.0.0 - 10.255.255.255 once you hit the 11.0.0.0 range you've left the private address range of class A that was set aside.

For Class B private address range its a /12 172.16.0.0 - 172.31.255.255 these are just set aside for private IP addresses. Class B does deal with the last two octets that's a /16, but only within class B's private range gives you the /12.

Class C private address range 192.168.0.0 - 192.168.255.255.

This is defined in RFC 1918.

Yes you're correct on the Class C address you will have 254 usable addresses, 1 for network, and 1 for broadcast.

But you're probably reading by now that CIDR and VLSM are used which can be confusing after learning classful addressing.

Jasiono

I used to be able to subnet rather quickly and efficiently in my head and I'm getting back into this all with the intent on finally taking the exam.

I studied for a test for school way back when and would probably do about 50-100 questions on subnettingquestions.com for several weeks straight, intended on taking the exam a year ago but stopped going to school and I lost a lot I've learned because I don't use it.

Thanks for that explanation. Those are something I never bothered with because of subnetting.

Jasiono

I see where my confusion came in.
This is private IP addressing which I have never seen (most likely didn't remember them LOL)

I was thinking about the other chart I learned previously, which is

Class A : 1 - 127.0.0.0/8
Class B: 128 - 191.0.0.0/16
Class C: 192 - 223.0.0.0/24
Class D and Class E, D for multicast and E for research, I think

mikeybinec

****1-126***

127 is the loopback on your host

Jasiono

This workbook has 127
blah