The security problems that outbreak network services today are increasing at a dramatic pace especially with the unceasing improvement of network transmission rates and the sheer amount of data exchanged. This translates not only more incidents but also new types of attacks with network incidents becoming more and more frequent. A significant part of the attacks occurs at Top Level Domains (TLDs) who have the assignment of ensuring the correct functioning of Domain Name System (DNS) zones. The proposed solution has been developed and tested at FCCN (Foundation for National Scientific Computing), the TLD manager for the .PT domain. The system consists of network sensors that monitor the network in real-time and can dynamically detect, prevent, or limit the scope of the attempted intrusions or other types of attacks to the DNS service, thus improving its global availability.