We found at least one "Open Recursive Name Server" which is capable to respond to any DNS lookup from any IP. This means that your DNS server will provide a DNS "Answer" for any domain if it is asked. This is a serious security vulnerability as it allows your system to be used for a DNS Amplification attack where someone will spoof an IP address and ask your DNS server for an answer. This could cause your DNS server to be slow or crash from the requests. It also causes your DNS server to send a DNS Response packet to the spoofed IP address. Since this packet is larger and the attacker is likely sending a lot of these, they have effectively used your system to DDOS the spoofed IP.