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DNS Research
Ongoing Research: DNS Monitoring and ProtectionThe main function of the Domain Name System (DNS) is to provide translation between Internet hostnames and IP addresses. Therefore, the DNS is a critical infrastructure service whose efficiency and robustness are crucial for the operation of the Internet. Despite the essential nature of the DNS, long-term research and analysis in support of its performance, stability, and security is extremely sparse. Our goal is to enable DNS research pertinent to real Internet problems by supplying the research community with the best available, operationally relevant and methodologically sound, measurement data. In addition, the tools, models, and analysis methodologies developed in the course of this project will contribute to ensuring the vitality and integrity of the DNS as it faces relentless growth of the Internet user population worldwide. CAIDA activities in the area of the DNS research currently are sponsored by the NSF grant SCI-0427144 "Improving the Integrity of Domain Name System (DNS) Monitoring and Protection". Research topics are:
Collaboration with NIC Chile and the .CL ccTLD DomainWe are studying the Chilean DNS data characterizing the .CL ccTLD domain in collaboration with NIC Chile. Our efforts include: 1) Analysis and indexing of daily packet traces captured on three anycast and one unicast name servers located in Chile. NIC Chile collected the traces daily at 12:10 pm local time from January 2005 till March 2007. Each 10-minute trace contains IPV4 traffic only and includes queries and responses with full payload; 2) anycast switching experiments conducted on the Chilean .CL ccTLD anycast infrastructure; and 3) DNS workload capture and visualization. Analysis of these data and indexing them in DatCat are in progress. During the period of this collaboration, we hope to conduct further analysis including usage and query rate trends, geographical and topological distribution of clients, and emerging traffic including EDNS0 support, DNSSEC related queries, Microsoft Active Directory SRV queries, IPv6-related queries and IDN. Analysis of DNS Root Server Traffic
DNS root servers are at the top of the DNS hierarchy. To characterize their workload and performance, we have undertaken the coordination of large-scale data collection events when participating operators captured concurrent traces from a large number of root server anycast instances. We conduct this work in collaboration with ISC and OARC. As of July 2007, there are two global DNS data sets, obtained in January of 2006 and 2007. We published the results of analysis of the first set. Analysis of the second data set is in progress. For each data set, we also developed Influence Maps of DNS anycast servers that visualize the geographic distribution of DNS clients for each anycast instance. We summarized our experience with large-scale simultaneous data collections in a set of recommendations intended to optimize collection strategies and to increase the research potential of future global multi-site coordinated data measurements. More information about analysis of DNS root server traffic More information about Influence maps of DNS anycast servers. DNS Surveys
One method of measuring the stability, validity and reliability of the Domain Name System (DNS) is to employ survey techniques to query the name servers for analysis and reporting. CAIDA employs several surveys to help us identify invalid data, analyze security issues, and determine the most commonly used software. Has your DNS server received a probe from a CAIDA host? Find out more about CAIDA's Open Resolver Survey. More information about DNS surveys. Anycast Modeling
In collaboration with CAIDA, Prof. George Riley and his student Sunitha Beeram from Georgia Tech University are conducting simulations of DNS anycasting methods. As of May 2006, they run experiments using a 44 node topology with 34 clients and 10 anycast server nodes. Simulations played out three different scenarios: no failures, a single link failure, and prefix withdrawal. Initial results show that, in the link down case, the distribution of requests among server nodes changes rather insignificantly: the clients can still reach the same servers through other links. In the explicit prefix withdrawal case, the network quickly converges to a new state since the simulated graph is small and strongly connected. The requests are re-distributed to other nodes with only one flip for affected clients. Future work will include adding scenarios for multiple network failures, modeling both global and local server nodes, and expansion to a larger, more realistic topology (using CAIDA AS-level graphs). RFC1918 Analysis
To service intra-enterprise networks that do not directly connect to the Internet, RFC 1918 establishes guidelines for address allocation for private internets. Unfortunately, some operating systems do not behave as expected and traffic that should stay within local area networks leaks onto the Internet at large. CAIDA researchers analyzed the properties and sources of spurious RFC1918 updates* that are directed toward the root name servers, and captured by a specially created protective system of name servers known as AS112. More information about RFC1918 analysis. DNS Measurement Software
DatasetsWe strongly encourage those with access to infrastructure to capture and document datasets to help preserve and promote scientifically rigorous, reproducible research. We encourage anyone who collects data to list the data in DatCat, the Internet Measurement Data Catalog. For specific recommendations on what type of metadata to include, refer to CAIDA's web page on How to Document a Data Collection. Our data collection efforts support the scientific Internet research community in the process of validating their models, simulations, or theories. The following DNS related CAIDA datasets are available for researchers.
Publications
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Cooperative Association for Internet Data Analysis (CAIDA)