root_servers are the root servers.
val ns_records : int32 * Domain_name.Host_set.t
ns_records is the root nameserver binding.
a_records is a list of names and bindings (A records) for the root servers.
aaaa_records is a list of names and bindings (AAAA records) for the root servers.
val ips : [ `Both | `Ipv4_only | `Ipv6_only ] -> Ipaddr.t list
ips ip_proto is a list of ip addresses of the root servers.
reserved_zones is a list of names and bindings for reserved zones specified by RFCs (private network address ranges, private domains)
val reserved : Dns_trie.t
reserved is a trie with all