docs: function goodbyes (name, packet) {
    return packet.answers.concat(packet.additionals)
      .filter(function (rr) {
        return rr.type === 'PTR' && rr.ttl === 0 && dnsEqual(rr.name, name)
      })
      .map(function (rr) {
        return rr.data
      })
  }