public String getNetProphetDnsInfo() {
   if (netProphetDns == null) {
     return "netProphetDns is NULL";
   }
   return String.format(
       "CurrentDNSTimeout: %d, RecordedDNSItemSize:%d, ViolatedItemSize:%d ",
       netProphetDns.getDnsTimeout(),
       netProphetDns.getdnsDelayItems().size(),
       netProphetDns.getLongDnsDelayItems().size());
 }
 public void debugTestingDNSServer(
     int maxDNSServerCount, int maxHostnameCount, List<String> hostnames) {
   netProphetDns.startDNSServerMeasurement(maxDNSServerCount, maxHostnameCount, hostnames);
 }