A longitudinal assessment of DNS resilience and robustness in Saudi Arabia.

As Saudi Arabia advances its digital transformation under Vision 2030, ensuring the resilience of its core Internet infrastructure becomes increasingly critical. Despite the strategic importance of the Domain Name System (DNS), the structural robustness of Saudi Arabia's DNS ecosystem has not been systematically evaluated. This paper presents the first large-scale measurement study of authoritative DNS resilience across the observable Saudi domain ecosystem, supported by longitudinal passive DNS data spanning 1994-2024. We propose a comprehensive DNS resilience assessment framework that combines active and passive measurements, analytical modeling, and controlled vulnerability testing. At the core of our methodology is DNSsifter, a custom multithreaded enumeration tool designed to expand domain visibility and uncover infrastructural dependencies. Leveraging a large-scale dataset comprising 25,811 Saudi seed domains and more than 37 million discovered subdomains, together with longitudinal passive DNS observations spanning 1994-2024, we compute DNS resilience metrics using a dedicated active measurement campaign conducted between September and December 2024. The historical dataset supports domain discovery and ecosystem evolution analysis, while the resilience assessment is derived from the active measurements across seven resilience dimensions: authoritative redundancy, delegation correctness, third-party dependency, parent-child consistency, Anycast deployment, DNSSEC adoption and validation, and caching efficiency. To enable holistic comparison, we introduce the Composite DNS Resilience Index (CDRI), a weighted composite index for quantifying multi-dimensional DNS resilience. Our findings reveal systemic weaknesses, including widespread delegation defects, limited DNSSEC adoption, uneven Anycast deployment, and insufficient redundancy in critical sectors. We conclude with strategic recommendations to enhance DNS resilience and support national cybersecurity priorities.