IP address ranges

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Hello.
In the new A+ 220-1101 course edutainer Wes Bryan says, that A class IP addresses are within the range 1.0.0.0 to 127.255.255.255. But my Google research and your Practice Test says different (1.0.0.0 - 126.255.255.255).
Which option is right?
Thank you!

@maksymilian-sybicki,

so...we take the binary of IP addresses....before the use of subnet masks were prevalent.

All of these addresses were categorized in the following way by using the 1st Octet.

If the 1st Octet begins with a 0 (zero) for a bits of binary

00000001 - 01111111 = Class A
So take the above 8 bits and convert these octets:
00000001 = 1.0.0.0
01111111 = 127.0.0.0

What google has done is decided to leave off the 127.0.0.0 network because it is a special network for loopack addresses.

If the 1st Octet begins with a 10 (one, zero) for a bits of binary

10000000 - 10111111 - Class B
So take the above 8 bits and convert these octets:
(You can do this on your own)

If the 1st Octet begins with a 110 (one, one and zero) for a bits of binary

11000000 - 11011111 - Class C
So take the above 8 bits and convert these octets:
(You can do this on your own)

@ronnie-wong,
wow, thanks a lot for the clarification! It's now easier for me to understand how these classes work, not just memorize the ranges. So on the A+ exam the ranges which will be passed are:
Class A: 1.0.0.0 - 127.255.255.255
Class B: 128.0.0.0 - 191.255.255.255
Class C: 192.0.0.0 - 223.255.255.255,
right?
And what about the addresses left (224.0.0.0 - 255.255.255.255)? Is there any class D or E and do I need to know these for the exam?
Thank you.

@maksymilian-sybicki said in IP address ranges:

@ronnie-wong,
wow, thanks a lot for the clarification! It's now easier for me to understand how these classes work, not just memorize the ranges. So on the A+ exam the ranges which will be passed are:
Class A: 1.0.0.0 - 127.255.255.255
Class B: 128.0.0.0 - 191.255.255.255
Class C: 192.0.0.0 - 223.255.255.255,
right?
And what about the addresses left (224.0.0.0 - 255.255.255.255)? Is there any class D or E and do I need to know these for the exam?
Thank you.

So here's what I would say about the exam....You'll probably see that the exam is not going to try and get you to commit to the 127.x.x.x. or 126.x.x.x. but will be which is a Class A or B....something like that.

But the above is the reality of how IP addresses are classified. ... now if they ask about a VALID class A....well that excludes the 127.x.x.x. network. hope that helps.

Those are special addresses in the fact class D is (224 - 239. then class is (240 - 255)...see if you can figure out the binary bits to classify these!

Thanks a lot!