--- bmanning(a)vacation.karoshi.com wrote: net 10 has flipped before, as has 192.0.0.0, and there remains flareups surrounding the 224.0.0.0 block. ----------------------------------------------- Can you elaborate? I don't seem to find much on search engines, except for these: http://www.faqs.org/rfcs/rfc3330.html " 192.0.0.0/24 - This block, corresponding to the numerically lowest of the former Class C addresses, was initially and is still reserved by the IANA." I also just finished detail-scanning rfc1597 and rfc1627 but found nothing regarding it. I also found http://ask.metafilter.com/111834/How-did-the-private-ip-address-ranges-get-s... which says: "10.0.0.0/8 was the old ARPANET, which they picked up on 01-Jan-1983. When they shut down the ARPANET in 1990, the 10.0.0.0/8 block was freed. There was much argument about if there should ever be private IP spaces, given that a goal of IPv4 was universal to all hosts on the net. In then end, practicality won out, and RFC 1597 reserved the now well known private address spaces. When ARPANET went away, the 10.0.0.0/8 allocation was marked as reserved and since it was known that the ARPANET was truly gone (the hosts being moved to MILNET, NSFNET or the Internet) it was decided that this was the best Class A block to allocate. Note Class A. This was before CIDR. So, the Class A, B and C private address netblocks needed to come out of the correct IP ranges. I know that 172.16.0.0/12 was picked because it offered the most continuous block of Class B (/16) addresses in the IP space that was in a reserved block. 192.0.0.0/24 was always reserved for the same reason that 0.0.0.0/8 and 128.0.0.0/16 were reserved (first blocks of the old Class C, A and B network blocks) so assigning 192.168.0.0/24 out as private fit well -- 192.0.2.0/24 was already TEST-NET, where you could use them in public documentation without fear of someone trying it (see example.com for another example.)" However, I don't know the validity of that. You've been around the IP block a time or two... ;-) Can you point me in the right direction? scott ----------------------- -------------------- -------------------