# "Modern DNS cache network": Nicaise Eric Choungmo Fofack, U. Nice Sophia Antipolis/ INRIA (France) (NRG Seminar)

Starts:
11:00 am on Monday, September 23, 2013
Ends:
12:00 pm on Monday, September 23, 2013
Location:
MCS 148
http://www-sop.inria.fr/members/Nicaise.Choungmo_Fofack Abstract: Caching is undoubtedly one of the most popular solution that easily scales up with a world-wide deployment of resources. The Domain Name System (DNS) is a well-known example of such cache deployment. Recent experiments on DNS hierarchy reveal that most of DNS caches over Internet have deviated from their traditional behavior by violating the Time-To-Live (TTL) rule specified in the RFC 6195. Theses DNS caches are called {\em modern DNS} in the literature. In this paper, we provide an analytic tool to assess the performance of the modern DNS hierarchy. We first introduce a class of expiration-based (or TTL-based) cache systems which enables us to describe the observed characteristics of modern DNS caches. We then compute the metrics of interest and establish several properties from the perspective of the modern caching hierarchy and end users, respectively using simple arguments of renewal theory. We evaluate our model on a single cache using real DNS traces and at network level through Event-driven and Monte-Carlo simulations, jointly used with Fourier Amplitude Sensitivity Test to explore the space of the input parameters. We observe that our analytic model predicts remarkably well all performance metrics at all caches of the network with relative errors smaller than $1\%$. Finally, we use our theoretic findings to characterize the optimal TTL configuration, explain some observed phenomenons and share the lessons learned on this modern DNS hierarchy. Bio: Graduated in June 2009, he got his Engineering degree in Telecommunications Systems and Networks form National School of Applied Science (ENSA) of Tanger. The year after in August 2010, he received the MSc degree in Ubiquitous Networking and Computing at University of Nice Sophia Antipolis (UNS). He was granted by The 2010 French Goverment MESR of the University of Nice Sophia Antipolis for a PhD. This PhD thesis is hosted in the team-project MAESTRO at INRIA Sophia Antipolis for the 3rd and last year. He received the Best student Paper Award of the 6th International Conference on Performance Evaluation Methodologies and Tools (ValueTools) 2012 for the paper "Analysis of TTL-based Cache Networks", joined work with Philippe Nain (his PhD advisor), Giovanni Neglia and Don Towsley (who he is currently visiting).