127.0.0.0/8 is earmarked for what is called "loopback". This construct is to allow a node to test/validate its IP stack. Most software only uses a single value from this range, 127.0.0.1/32 for loopback purposes. It is treated with the same levels of restriction by router and host requirements and implementations so it is difficult to use any other addresses within this block for anything other than node specific applications, generally bootstraping. All in all a tremendous waste of IP space. Good thing we'll not likely need it. (excerpt taken from draft-manning-dsua-00.txt, "Documenting Special Use IPv4 Address Blocks") Thanks. IANA