5

I was just reading RFC4632 "2. History and Problem Description" and I don't get the part about Class A with MSB '00'. That would in my understanding mean, there are actually only 64 available networks, which collides with my knowledge, that there are more /8 networks actually. The RFC also suggest, there are 128 possible networks in Class A, which would mean, there is only one MSB '0' e.g. From what I read in older RFCs, such as RFC1166 section Network Numbers, there is only MSB '0' in Class A.

So what have I missed? In case, the RFC would be incorrect, whom should I contact to correct it?

8

It appears to be a typo in that RFC. Notice that the header of the RFC says Errata Exist. It is not uncommon for things like that to happen.

That particular error is corrected in the errata. See the RFC Editor for the details.

Errata ID: 3485
Status: Verified
Type: Technical

Reported By: Markus Falb
Date Reported: 2013-02-18
Verifier Name: RonBonica
Date Verified: 2013-02-18

Section 2 says:

three classes of networks: Class A  
(most significant address bits '00'), with 128 possible networks each  
and 16777216 end systems

<
It should say:

three classes of networks: Class A  
(most significant address bit '0'), with 128 possible networks each  
and 16777216 end systems

<
Notes:

MSB bits ’00’ would mean that only 6 bits are available for the network part and this would mean only 64 CLASS A networks.

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