[Feedback]: CIDR Vs Classfull #38
Description
Question or Feedback
Love the tool. I now keep it on my laptop because I often use a subnet calculator.
Please please please remove the "Class _" references from all of the tooling.
RFC791
... An address begins with a network number, followed by local address (called the "rest" field). There are three formats or classes of internet addresses: in class a, the high order bit is zero, the next 7 bits are the network, and the last 24 bits are the local address; in class b, the high order two bits are one-zero, the next 14 bits are the network and the last 16 bits are the local address; in class c, the high order three bits are one-one-zero, the next 21 bits are the network and the last 8 bits are the local address...
If you write out addresses in binary this is the result:
| First Octet | Class | First Octet Network Bits |
|---|---|---|
| 0-127 | A | 0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH |
| 128-191 | B | 10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH |
| 192-223 | C | 110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH |
That means, for example, 10.x.x.x can not exist in the class B range.
Having labeling that says "/8 (Class A)" is just plain incorrect. Also, it's just not used any more.