Counting in the Dark: DNS Caches Discovery and Enumeration in the Internet

Domain Name System (DNS) is a fundamental element of the Internet providing lookup services for end users as well as for a multitude of applications, systems and security mechanisms that depend on DNS, such as antispam defences, routing security, firewalls, certificates and more. Caches constitute a critical component of DNS, allowing to improve efficiency and reduce latency and traffic in the Internet. Understanding the behaviour, configurations and topologies of caches in the DNS platforms in the Internet is important for efficiency and security of Internet users and services. In this work we present methodologies for efficiently discovering and enumerating the caches of the DNS resolution platforms in the Internet. We apply our techniques and methodologies for studying caches in popular DNS resolution platforms in the Internet. Our study includes networks of major ISPs, enterprises and professionally managed open DNS resolvers. The results of our Internet measurements shed light on architectures and configurations of the caches in DNS resolution platforms.