code: def _get_nameservers(domain):
          
          nameservers = []
          rdtypes_ns = ['SOA', 'NS']
          rdtypes_ip = ['A', 'AAAA']
          for rdtype_ns in rdtypes_ns:
              for rdata_ns in Provider._dns_lookup(domain, rdtype_ns):
                  for rdtype_ip in rdtypes_ip:
                      for rdata_ip in Provider._dns_lookup(rdata_ns.to_text().split(' ')[0],
                                                           rdtype_ip):
                          if rdata_ip.to_text() not in nameservers:
                              nameservers.append(rdata_ip.to_text())
          LOGGER.debug('DNS Lookup => %s IN NS %s', domain, ' '.join(nameservers))
          return nameservers
docs: Looks for domain nameservers and returns the IPs of the nameservers as a list.
          The list is empty, if no nameservers were found. Needed associated domain zone
          name for lookup.