To configure GSLB Load balancing to respond to both IPv4 and IPv6 DNS queries. The GSLB service may or may not be on the NetScaler appliance

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Instructions

The GSLB virtual server has a DNS record type which can only return the IP address as per the record type. The A record type (IPv4) GSLB VServer can respond to only IPv4 queries, whereas the AAAA record type GSLB VServer can only respond to IPv6 DNS queries. Thereby, for the setup two GSLB Virtual servers are required.

1. Create a GSLB service with IPv4 address. This service can be a NetScaler LB/Gateway Virtual server or a back-end server added as a server on NetScaler.
2. Similarly, create a GSLB service with IPv6 address server.
3. Next, create a GSLB Virtual server. Provide the DNS address record type as 'A' record. Bind the IPv4 GSLB service to it. Bind the ADNS service. Then, bind the FQDN in the domain binding.
4. Further, create another GSLB Virtual server and provide the DNS record type as 'AAAA' record. Bind the IPv6 GSLB service to it. Next, provide the same ADNS and same FQDN in the domain binding as in step 3.

The same can be done for both local and remote sites and accordingly multiple GSLB services can be bound to the GSLB Virtual server.
The DNS query request when sent from a machine, if IPv6 enabled, will be sent for both 'A' and 'AAAA' type. These queries will come to the NetScaler ADNS. The IPv4 query will be responded by the GSLB Virtual server with record type as 'A', whereas the IPv6 query will be responded by the other GSLB Virtual server for which the record type is 'AAAA'.

The ADNS for the setup can be IPv4 itself. The DNS server just should be configured to send all DNS requests (A or AAAA) to the ADNS i.e. on the NetScaler.

How to make the GSLB respond to both IPv4 and IPv6 DNS queries for the same FQDN.