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    For the curious, 10/8 used to be public, but I wrote about how it became private.

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      I wondered about private network assignments after reading this recent curl post about IP address formats. 192.168. corresponding to octal 0300.0250. sparked my interest!

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        The RFC 1918 on private IPv4 ranges might be interesting to read, https://tools.ietf.org/html/rfc1918 The 10.x.x.x/8 is intuitive, but I’m not sure why 192.168.x.x/16 and 172.16.x.x/12 were chosen

        For that matter, I’m also curious why 169.x.x.x was chosen for IPv4 link local addresses

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          The coauthor of 1918 replied in the linked thread:

          The RFC explains the reason why we chose three ranges from “Class A,B & C” respectively: CIDR had been specified but had not been widely implemented. There was a significant amount of equipment out there that still was “classful”.

          As far as I recall the choice of the particular ranges went as follows:

          10/8: the ARPANET had just been turned off. One of us suggested it and Jon considered this a good re-use of this “historical” address block. We also suspected that “net 10” might have been hard coded in some places, so re-using it for private address space rather than in inter-AS routing might have the slight advantage of keeping such silliness local.

          172.16/12: the lowest unallocated /12 in class B space.

          192.168/16: the lowest unallocated /16 in class C block 192/8.

          In summary: IANA allocated this space just as it would have for any other purpose. As the IANA, Jon was very consistent unless there was a really good reason to be creative.

          Daniel (co-author of RFC1918)

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          I don’t know why, but it always amuses me that its a nice looking binary number.

          11000000.10101000. (192.168.)

          10101100.00010000 (172.16.)

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            You can find beauty in many binary numbers

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              192 is a nice number like that because it’s at the bottom of the Class C space, and the classes were delimited in nice ways (they had prefixes 0, 10, 110, and 1110, leaving 1111 as “experimental” / future use).

              The other ones are, judging from this comment, coincidental: the lowest class B network was 128.0.0.0/12, but evidently everything from 128 up to 172-and-change (705 networks or so) had already been given out, as had the first 165 class Cs (back then, no one had much reason to stick themselves with just a /24).