You may be able to use this https://dnscrypt.eu/ instead of hard-wiring Google in directly. Also, the Czech fellows who used to make DNSSEC Validator provided 2 IP4 and 2 IP6 machines to go with that. Other that supporting DNSSEC those are simply public DNS servers like Google's and there is nothing to enforce the use of their own plug-in. The addresses are in their documentation. (Actually, they may have a whole bunch more on the account of being people who run .cz TLD registry. AFAIK, the Czechs are the only TLD registry that support regular, documented version of DNSSEC, though there is a whole bunch more using some slightly hacked version of their own)