type Dns::Zoneentry = Struct[{
    mname         => String,
    rname         => String,
    ns            => Optional[Array[String]],
    records       => Optional[Array[Dns::Recordentry]],
    update_policy => Optional[String],
    refresh       => Dns::Ttl,
    retry         => Dns::Ttl,
    expire        => Dns::Ttl,
    negative_ttl  => Dns::Ttl,
    ttl           => Dns::Ttl,
}]