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Announcing Windows CLAT Public Preview

JimAlumbaugh's avatar
JimAlumbaugh
Icon for Microsoft rankMicrosoft
Jun 09, 2026

In November 2025, we announced the private preview of Windows CLAT, marking a major milestone in helping customers operate successfully on IPv6-only and IPv6‑mostly networks.

Since then, we’ve worked closely with customers across government, enterprise, and the broader internet community to validate the feature, refine the experience, and ensure it’s ready to scale. If ...
Updated Jun 17, 2026
Version 3.0
JimAlumbaugh's avatar
JimAlumbaugh
Icon for Microsoft rankMicrosoft
Jun 17, 2026

hi saxl23​, do you mind reaching out to me directly? I'd like to understand more about this issue. Thank you!

swalker_aup's avatar
swalker_aup
Copper Contributor
Oct 04, 2026

Hi Jim,

In my testing, it seems that when using the CLAT, my Windows client (my testing version is 10.0.26200.9448) is still exhibiting the DNS behaviour mentioned by saxl23​ : in our environment, where computers are Active Directory domain-joined and the DNS servers are serving AD-integrated DNS zones, computers that have the CLAT enabled are registering their hostnames in the DNS zones using two addresses:

  • A real, unique IPv6 address (which is what we want)
  • The CLAT's internal 192.0.0.1 IPv4 address (not desirable as it is useless outside of the client itself: it is like registering "127.0.0.1" as a computer's name in DNS.)

For example, if my computer's name is TEST-LAPTOP.ad.contoso.com, if I receive the IPv6 address of 2001:db8:cof:fee:1:2:3:4, and the CLAT is activated when I connect to the network due to activating PREF64 and DHCP option 108, performing a DNS lookup for "TEST-LAPTOP.ad.contoso.com" will return two records:

  • AAAA: 2001:db8:cof:fee:1:2:3:4
  • A: 192.0.0.1

The second record is useless to all other devices on the network.  Ideally, the computer should never register an IPv4 CLAT address like 192.0.0.1 in DNS, the same way it wouldn't register the address 127.0.0.1.

Is Microsoft aware of this issue?