Google's IPv6 DNS addresses suddenly appearing on client machines

[Meldrew]

Hi.

 

Bit of a weird one. We're having random PCs fail to access the Internet, reporting unable to access proxy server. Upon investigation, the PCs have 2 extra DNS servers - google's IPv6 DNS servers: 2001:4860:4860::8888 and 2001:4860:4860::8844 in their DNS servers and an additional default gateway (also IPv6). We've checked the DHCP server to ensure that the settings aren't in there somehow and we can't see anything, but the issue appears to be spreading. We did reboot the server with DHCP on it this morning (as it had Azure AD connect on it which had stopped replicating changes) which kind of makes us wonder if this was the trigger.

 

We've checked and the server doesn't have IPV6 enabled. On an affected PC, release and renewing the address makes no difference; the IPV6 addresses come back, however disabling IPv6 on an affected PC, then release and renewing and re-enabling IPv6 seems to have helped.

 

Also, the IPV6 default gateway won't ping.

 

Any thoughts?

 

Meldrew

[Meldrew]

Sorted. Turned out to be a router which had a separate IPv6 and IPv4 DHCP server , plus a lack of understanding on our part about quite how IPv6 works.

[Steve21]

You got chrome installed? Did you turn off the use own dns options via GPO? Just a thought being Google related

 

Steve