This was upgraded on 28 January 2013, when Google's DNS servers silently started providing DNSSEC validation information, but only if the client explicitly set the DNSSEC OK (DO) flag on its query.
2013年1月28日这种情况得到改进，当时Google的DNS服务器静默启动DNSSEC验证信息的供应，但是只有客户端启动DNSSEC OK (DO) flag时生效。