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My Windows system got an 169.xx.xx.xx IP address the other day, and I fixed the issue, but why did Microsoft chose this address as the default?

Why not 1.xx.xx.xx or 255.xx.xx.xx? Did one guy at Microsoft say

Hey, pick a number 1 to 255....who just said 169?! OK, we're going with that for our Windows default IP address.

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    It's actually not always 169.xx.xx.xx there's also 192.168.xx.xx that I've seen.
    – James Mertz
    Commented Jan 27, 2011 at 19:28
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    169.xx.xx.xx are very specific in their use and function though and not directly related to the use of the 192.168.xx.xx address schema
    – Linker3000
    Commented Jan 27, 2011 at 19:32
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    Yeah, no, KronoS -- you've never seen Windows automatically assign itself a 192.168 IP address... it doesn't do that.
    – delfuego
    Commented Jan 28, 2011 at 2:35
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    @KronoS, you're missing the point. 192.x addresses are real. 169.x default addresses mean the computer isn't actually connected to a network.
    – CarlF
    Commented Apr 11, 2011 at 12:31
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    192.168.0.0/24 has NOTHING to do with the reason why 169.254.0.0/24 exists. The ONLY thing they have in common is that they are nonroutable. Stop confusing the two. Windows will never assign itself a 192.168.0.0/24 address. Neither with Microsoft. It always comes from a router or a manual IP assignment.
    – LawrenceC
    Commented Jun 18, 2012 at 12:55

3 Answers 3

Reset to default
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It's not MS it is the ISOC ;-)

Have a look at reserved IP address RFC 5735 under special use IPv4: here

169.254.0.0/16 - This is the "link local" block. As described in [RFC3927], it is allocated for communication between hosts on a single link. Hosts obtain these addresses by auto-configuration, such as when a DHCP server cannot be found.

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    I first came across this address space when Apple introduced Bonjour.
    – user11088
    Commented Jan 28, 2011 at 2:38
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    That only defers the description of “why”, though: why did RFC 5735 allocate this specific “magic number” for this use? What’s the rationale?
    – Konrad Rudolph
    Commented Jan 28, 2011 at 14:13
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    @Konrad - I suspect part of the rationale was that it was available.
    – Rob Moir
    Commented Jan 28, 2011 at 15:17
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    @Konrad - RFC 5735 is more of a collection of RFC's that pertain to special use netblocks. The actual "meat and potatoes" if you will can be found in RFC 3927 which is linked directly from 5735. As for why the IETF picked this address space for Link local? I can't find the reasoning.
    – user61724
    Commented Jan 28, 2011 at 15:47
  • @DanM., What does "link local" mean anyway? How does 192 differ from 169?
    – Pacerier
    Commented Nov 12, 2017 at 13:44
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The use of 169.x.x.x addresses are defined within a standard colloquially known as APIPA - Automatic Private IP Addressing.

In a nutshell, if a network device has not been assigned a fixed (static) address and cannot obtain one by asking (DHCP), the device says to itself, "Well, I'd better make up an address of my own so I can communicate on this network", so it assigns itself an APIPA address, which start at 169.254.0.1 and run up to 169.254.255.254.

If you suddenly find your computer has an address within the AIPIA range it usually means that the device on the network dishing out addresses (the DHCP server) is not contactable for some reason; it may be switched off or your network cable has become disconnected, for example.

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    Do you mean that once they are able to talk to DHCP, they change from 169 to 192? Is this a standard or is it just by custom? What if he doesn't change even after talking to DHCP?
    – Pacerier
    Commented Nov 12, 2017 at 13:45
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To state Dan M's answer in another terms, your DHCP server has a problem and cannot allocate an IP address. When Windows and any other OS is configured to get an IP via DHCP and they don't get any, they automatically assign 169.254.xxx.xxx IP

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    I think you mean Dan M. There is also the alternative that you don't have a DHCP server on the network.
    – Samuel Harmer
    Commented Mar 6, 2015 at 15:24

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