I have a Vigor2927 with firmware 4.4.2.

I have a problem with “Conditional DNS Forwarding” and IPv6.

I have a local domain with two DNS servers which resolve my local domain and forward all other requests to Google DNS servers supporting IPv4 and IPv6 requests.

If I set the 2927’s DHCP server to issue the IPv4 and IPv6 addresses of my local DNS servers, then all IPv4 and IPv6 internal and external access is fine.

I would prefer to have DHCP issue Google DNS servers i.e., 8.8.8.8, 8.8.4.4, 2001:4860:4860::8888 and 2001:4860:4860::8844 combined with the 2927 using Conditional DNS Forwarding to pass DNS requests for my local domain to one of my local DNS servers.

If a host issues an IPv4 DNS request (i.e., using IPv4 to make the DNS request not just asking for an A rather than AAAA record) all works fine for targets in the local domain and WAN.

If a host issues and IPv6 DNS request it works fine for WAN targets. However, the 2927 does not pass local domain requests to my local DNS server, it passes them to Google where they fail.

If I use nslookup to send DNS requests to the 2927’s LAN IPv4 interface it responds correctly for local domain and WAN targets. The 2927 does not respond to nslookup on its LAN IPv6 interface, it returns an ICMPv6 saying “Port not found”.

I have confirmed that the 2927’s DNS filter is correctly trapping IPv6 DNS requests using Cyren.

I have tried configuring two DNS forwarding rules with the IPv4 and IPv6 address of a local DNS server, but problem remains.

Has anyone else used Conditional DNS Forwarding with IPv6 DNS server addresses?