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Despite having a valid IPv6 address and being able to communicate with other IPv6 hosts, a Windows 10 system on my LAN is igonring AAAA responses and as such will not initiate IPv6 traffic.

  • nslookup will show the A record for a domain, but not the AAAA record, even though I can see in Wireshark that the AAAA query is sent and a valid response is received.
  • Reverse nslookup works as expected and if I query an IPv6 address I get back the expected hostname.
  • ping -6 works when I go directly to another IPv6 address, but not when I enter a hostname. This is likely an artifact of the ignored AAAA response mentioned above.
  • IPv4 works as expected.
  • Dual-stack Linux and BSD systems on the same subnet with the same nameserver work as expected.

I found this (https://support.microsoft.com/en-us/help/929852/guidance-for-configuring-ipv6-in-windows-for-advanced-users) about preferring IPv4 over IPv6, but I do not have those registry keys set.

Edit: Does it matter that my nameservers only listen on IPv4?

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PS C:\Users\John> nslookup -type=AAAA google.com
Server:  UnKnown
Address:  fe80::d66e:eff:fe35:c5d4

Non-authoritative answer:
Name:    google.com
Address:  2607:f8b0:4009:80e::200e

Without a type parameter, nslookup will return A record if one exists. I assume that is for compatibility because someone relies on the default behavior.

(I found nslookup's usage message and online documentation useless. At least type examples are available from third parties.)

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  • This does not work for me: can't find www.google.com: Not implemented
    – Agrajag9
    Jul 29 '19 at 12:06
  • What nslookup command are you running? In a packet capture what queries do you see on the wire? Jul 29 '19 at 15:22
  • >nslookup www.google.com 1.1.1.1 Server: one.one.one.one Address: 1.1.1.1 Non-authoritative answer: Name: www.google.com Address: 172.217.15.100
    – Agrajag9
    Jul 29 '19 at 17:50
  • Everything works as expected when adding an IPv6 nameserver. It seems that Windows does not support AAAA over v4, only A over v4 and AAAA over v6.
    – Agrajag9
    Jul 29 '19 at 17:53
  • I get IPv6 addresses just fine from several public DNS services over v4. -type=AAAA seems to be required. Jul 30 '19 at 0:41

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