Server 2016, this is our SCCM server. I'm attempting to troubleshoot an issue with our SCCM instance and I notice that the IPv6 Link-Local address contains the word 'bad' at the end.

I can literally find no mention of this anywhere. Can anyone explain that?

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  • 3
    IPv6 addresses are hexadecimal digits that include the letters a..f. You can get different words in there. The classic example is dead:beef. It doesn't actually mean it is a bad address.. Also, you never need to obfuscate link-local addresses because every link has the same network, and nothing can be routed to link-local networks. – Ron Maupin Jan 30 '19 at 4:43
  • Apparently, the "number after the '%' is the scope ID," see Why is there a percent sign '%' in the IPv6 address? on SuperUser, and the "bad4" part including "bad" is just a coincidence. – Colt Jan 30 '19 at 4:48
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    How about some c0:ffee? deca:fbad. dead:beef for lunch... – Michael Hampton Jan 30 '19 at 15:24
  • fe80::b01d:face:c0de – Colt Jan 30 '19 at 15:37
  • its not bad it was born that way! :P – Jim B Jan 30 '19 at 20:06

That isn't an issue, it's just a random thing that can happen because IPv6. I'm not sure why the initial answers on this were given in the form of comments, but whatever.

IPv6 addresses are 128 bits long. If they were given in the same format as an IPv4 address, that would come out to something like

To make that shorter, they use base 16, which borrows the letters a-f for the extra six digits. They also put in another trick: the largest range of consecutive 0000 blocks can be simply eliminated, just marked by having a double colon. Because even


is pretty ridiculously long. Note by the way, there's also a 'd' and an 'a' apart from the 'bad' you noticed. So with the zero reduction, we get

  • facebook.com has IPv6 address 2a03:2880:f11b:83:face:b00c:0:25de Note facebook -> face:b00c Somebody did that, just because you can. – Lenne Jan 30 '19 at 9:51
  • Great, thanks for taking the time. It was a peripheral issue while I was troubleshooting something else. Just a weird coincidence! – mhouston100 Jan 31 '19 at 8:59

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