DNS Topology Load Balancing for enterprise WIFI using OpenDNS Public DNS Servers

Hi experts,

Have any of you implemented or considered Topology load balancing for enterprise WIFI (Nationwide) where WIFI clients are using OpenDNS public DNS servers?

Here is the environment.

Target application is F5 DNS WIP, example.xyz.com.

Two data centers, one is at Colorado Data Center (DC2) and the other is at Kansas City Data Center (DC2). Each data center has F5 DNS (DNS1 at DC1 and DNS2 at DC2)

Enterprise WIFI has been setup nationwide, WIFI1. When client machines are connected to WIFI1, OpenDNS Public DNS servers are associated (208.67.222.220 and 208.67.222.222)

Now the goal is when client machines close to DC1, say California, need to access example.xyz.com, IP address of example.xyz.com at DC1 is provided. Similarly if client machines close to DC2, say New York, need to access example.xyz.com, IP address of example.xyz.com at DC2 is provided.

Here is the challenge.

As OpenDNS has its own big big DNS infrastructure/environment, we cannot tell what would be the last LDNS IP address(es)/subnet making DNS query to my DNS/GTM. We may think of using State as the source of DNS query. However we don't know if last LDNS of OpenDNS DNS servers is geo-location recognizable.

WIFI Client (query: example.xyz.com) ---> [ OpenDNS DNS cluster {OpenDNS (208.67.222.220) ...... Last LDNS: 204.194.238.168} ] ---> F5 DNS/GTM

Any idea or suggestion will be really appreciated.