URL: http://www.caida.org/publications/papers/2001/Rssac2001a/ Entry Date: 2003-10-02 Abstract: We describe active measurements of topology and end-to-end latency characteristics between several of the DNS root servers and a subset of their clients using the skitter tool developed by CAIDA. We gather a sample of clients for each monitored DNS root server, combine these samples into a common target list and then actively probe these targets and analyze their connectivity. We identify the subsets of destinations that have large latency connections to all instrumented root name servers and discuss their geographical make-up. Our goal is to build an analytical framework for evaluating the optimality of root server placement and its impact on the efficiency of the DNS service. The skitter tool and the methodology we propose can also be used for monitoring the end-to-end performance in large networks and for assessing the optimality of web servers placement in general.