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Were there any particular reasons that 169.254.x.x was chosen as self-assigned IP? Its binary form doesn't look nearly as "whole number-ish" as other commonly used IPs like 127.0.0.1 or 192.168.0/1.1.

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Perhaps there weren't many unallocated ranges to choose from at that point? –  grawity Mar 12 '12 at 23:15
    
It can't use any of those. Those are reserved. –  Wuffers Mar 13 '12 at 0:26
    
ietf.org/rfc/rfc3927.txt –  Tom Wijsman Mar 13 '12 at 4:10
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closed as not constructive by slhck, Simon Sheehan, techie007, Wuffers, Tom Wijsman Mar 13 '12 at 4:07

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3 Answers

up vote 6 down vote accepted

The private IP addresses were reserved in the early 1990's. IPv4 link-local addresses weren't added until 2005.

The block chosen, 169.254.0.0/16, was obtained simply by requesting a block from IANA and having one allocated through the normal allocation process. So it was essentially random, rather than engineered.

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I don't have an authoritative source to cite at this time, but as I recall, it was a netblock that had already been allocated to Microsoft, and Microsoft was one of the key advocates of IPv4 link-local addressing, and had implemented it in their own products using their own netblock, and then "gave it back" to IANA as the IETF adopted the Internet-Draft that became RFC 3927.

With enough Googling, you can probably find some emails from the mid-1990's about this, on some IETF mailing list, probably from Bernard Aboba at Microsoft. This feature first shipped in Mac OS 8.5 in the summer of 1997, and then a year later in Windows 98 in the summer of 1998. So look for emails from 1995-1997 and you can probably find something more authoritative than my fuzzy recollections.

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169.254/16 is part of an IP block assigned to the IANA themselves. The IANA set the standards for various networking rules, including the Automatic Private IP Addressing rules which 169.254/16 comes from.

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