Robust or Risky: Measurement and Analysis of Domain Resolution Dependency

DNS relies on domain delegation for good scalability, where domains delegate their resolution service to authoritative nameservers. However, such delegations lead to complex inter-dependencies between DNS zones. While a complex dependency might improve the robustness of domain resolution, it could also introduce security risks unexpectedly. In this work, we perform a large-scale measurement on nearly 217M domains to analyze their resolution dependencies at both zone level and infrastructure level. According to our analysis, domains under country-code TLDs and new generic TLDs generally present more complicated dependency relationships. For robustness consideration, popular domains prefer to configure more complex dependencies. However, the centralization of nameserver hosting and the silent outsourcing of DNS providers could lead to severe false redundancy at infrastructure level. Worse, considerable domain configurations in the wild are "not robust but risky": a more complex dependency may also indicate more vulnerabilities, e.g., domains with a 2× higher dependency complexity have a 2.87× larger proportion suffering from the hijacking risk brought by lame delegation.