Measuring Update Performance and Consistency Anomalies in Managed DNS Services

Managed DNS (MDNS) services today excel at providing a simple and cost-effective way to outsource domain management and ensure rapid lookup times for geo-distributed users. The intense focus on optimizing lookup performance coupled with DNS’ inherent expectations of weak consistency has had unfortunate side effects: updates are inexplicably slow and MDNS providers pay scant attention to consistency correctness. We conduct an empirical measurement-driven study of 8 top-tier managed DNS providers and find that inter-nameserver update propagation delays commonly take tens of seconds with little improvement over the last several years. Client-perceived inconsistency is rampant with roughly a third of end-users being vulnerable to TTL abuse by local DNS resolvers. Furthermore, we find that 6 of the 8 MDNS providers violate monotonic read consistency under frequent updates and at least one large MDNS provider appears to violate even eventual consistency.