A Global Reference Model of the DNS

The Domain Name System (DNS) is a crucial component of today’s Internet. At this point in time the DNS is facing major changes such as the introduction of DNSSEC and Internationalized Domain Name extensions (IDNs), the adoption of IPv6 and the upcoming extension of new generic Top-Level Domains. These changes can have impact on the behaviour of the DNS. In this paper we present a first global DNS reference model with the aim to predict the DNS traffic behaviour under specific conditions. In fact, this quantitative model is intended to be used for analyzing what-if scenarios. For example, how will DNS query rates at the recursive and authoritative name servers increase in case DNSSEC validation errors lead to sending more Servfail responses towards DNS clients? The DNS reference model takes into account all relevant components present in the DNS architecture. To characterize the system variables describing the query behaviour at each of these independent system components, we statistically analyze real world data from recursive resolvers. In addition, we use experimental results that characterize DNS client behaviour and data from the literature to characterize the behaviour of authoritative name servers. In order to validate our reference model we compare the model predictions to the real world data. The validation results show that the model predictions are rather accurate. At the end of the paper we present a specific what-if scenario to demonstrate the applicability of the model