# Reasons behind the choice of 172.16/192.168? [closed]

It is a known fact that there are three blocks of IPv4 Addresses that were chosen to be reserved for private networks:

 10.0.0.0        -   10.255.255.255  (10/8 prefix)
172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
192.168.0.0     -   192.168.255.255 (192.168/16 prefix)


(as specified by RFC 1918). However, although I can sort of see why 10.0.0.0 would be a natural choice, I can think of no particular reason why 172.16.0.0 and 192.168.0.0 were chosen among all the possibilities. I tried to google about this but got nothing, and the RFC document did not provide any explanation either. Was it really just a random decision?

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I think this is a very good question, and it should be on-topic here. – Jukka Suomela Dec 31 '12 at 15:57
@JukkaSuomela I don't see why: this is about industrial history, there's no science here. – Gilles Dec 31 '12 at 16:41
@Gilles: First of all, the question is not just about some industrial history, but it is about the history of computing. But most importantly, the question is of interest from the perspective of network sciences: Network scientists want to understand not only the structure of the Internet that all of us can see today, but they also want to understand why it looks like this and how it has changed. Sure, there is a strong social science aspect here, but nevertheless we have both the computing aspect and the science aspect here, even if this is not hard-core computer science. – Jukka Suomela Dec 31 '12 at 17:04
@JukkaSuomela We've already discussed this on meta: Should questions about CS-related standards be allowed? This question is even less sciency: what makes it on-topic? It's about computing, sure, but how is it about computer science? (By the way, I suspect the answer involves “these ranges weren't assigned yet”.) – Gilles Jan 1 at 22:00
@Gilles: The meta discussion is about a question of the form "what is written in standard X", while this question is of the form "why this-and-that is written in standard X". I agree that technical details that you can easily look up are not of great interest here. However, the reasons behind the particular choices are often interesting. (For example, in this case one factor was pre-CIDR Internet and the need to have private networks in each of the traditional classes A, B, and C. They were not looking for just some free address ranges.) – Jukka Suomela Jan 2 at 0:17

## closed as off topic by Niel de Beaudrap, Jernej, Vor, Luke Mathieson, AProgrammerDec 31 '12 at 15:36

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