Can you give us more example, what you trying to achieve to understand better.
Are you looking DNS Lookup or Routing Traffic ?
Its a DNS resolving issue and not a routing issue. We want clients (or proxy for these clients) to do DNS resolving on a DNS server which is not on the Internet but exists in a specific network, outside of our network infrastructure and maintained by a third party.
If this is not FQDN and your own DNS Service, make sure WSA able to reach that WebServices -
you should able to put in order of DNS List.
test and advise any issue.