Availability and effectiveness of root DNS servers: A long term study

Domain Name Systems (DNS) servers provide a critical service to users and application on the internet. At the top of the DNS hierarchy is the Root DNS servers providing pointers to Top Level Domain servers on the Internet. Over the past years the number of Root DNS servers has grown to cope with the exponential growth of the Internet. This paper reports on the status and performance of the Root DNS servers gathered by the Gulliver´s project SEIL probes which are deployed globally. This is the first effort to carry out long term study, from 2007 till 2009, on the performance of Root DNS servers. The data gathered shows the performance of anycast Root DNS servers in terms of Loss Rate and Query Response Time (QRT). Anycast servers´ performance on the whole has been improving with more deployment of its instances, while unicast servers´ performance has been roughly the same. We have correlated changes in the QRT to events that has occurred, eg. Cable breaks and deployment of a new anycast instance.