Why did the IANA choose the obscure numbers 192.168.* 172.16.* and 10.* for the reserved local address ranges?

Question

I amawear that the Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets:

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)

These will not be used on a global IP network

RFC1918 faq
http://www.faqs.org/rfcs/rfc1918.html...

But why such obscure numbers rathern than say:

1.0.0.*
2.0.0.*
etc.

Cheers,
Jon

Answer 1

Because the addresses are for different classes of addressing, class A, Class B, and Class C allowing for different sized address spaces and subnetting.

So a very large network may need to use a 10.x.x.x address to have all there network nodes in one address space.
Most routers use a default of 192.168.x.x and a subnet of 255.255.255.0 as most commonly there is plently of address space available (256 nodes).

Exactly why the decision was made in this way I do not know.

Answer 2

Maybe this will help you out a little bit. Most of the numbers were reserved by the military and government and therefor could not be used for private networking.

http://www.iana.org/assignments/ipv4-address-space

Answer 3

Probably because they were unassigned and therefore available at the time that the RFC 1918 standard was established.

Answer 4

Might be clearer in hex decim.
0A.0.0.0
AC.20.FF.FF
B0.D0.FF.FF