[dns-operations] c.root-servers.net over IPv6

[SM]

Hello,

c.root-servers.net (2001:500:2::c) is not responding to queries over IPv6 [1].

Regards,
-sm

1. The error from DNSViz is "arpa zone: The server(s) were not 
responsive to queries over UDP. (2001:500:2::c)"