How the ProxySG performs and requests DNS Recursion.

DNS recursion on the proxy
    The proxy will perform a DNS lookup to the IP address of the authoritative name server IP address that the DNS servers responds with (only when it doesn't respond with an A record). If its not enabled the proxy will not do this.

DNS recursion in the query
    The Recursion desired flag in the DNS request made by the proxy to any of the DNS servers is always turned on because we are asking the DNS server we are querying to perform DNS recursion but if it is configured not to do so, it will return the authoritative name server for the queried host and we can either perform the recursion ourselves "if" we are configured to do so....or not.