Title: Contextualizing Anycast Performance

Abstract

IP anycast enables a single service address to be advertised across multiple physical locations, relying on BGP to direct each client to the most appropriate site. While this routing mechanism is foundational to the DNS root server infrastructure, public resolvers, and certain content delivery networks (CDNs), its impact varies significantly depending on the application. This study evaluates anycast latency in two distinct environments: the root DNS system, where recursive caching mitigates root-server delays for users over extended periods via long TTLs, and CDNs, where every extra round trip can directly impair page loading, video buffering, or API response times.

Our analysis reveals that while root DNS anycast may involve considerable path inflation, the resulting delay remains minimal for end-users. In contrast, CDN anycast demands proactive engineering—specifically in peering, route policies, catchment scope, and measurement feedback—to prevent excessive latency inflation. The paper presents a comparative latency model, a reproducible measurement methodology, and an optimization framework that distinguishes between resilience-focused and latency-focused anycast goals. The primary takeaway is operational: root DNS and CDN anycast should not be optimized using a unified objective function. For root DNS, priorities include robustness, reachability, and caching dynamics; for CDN services, the focus must shift to tail latency, accurate catchment, and policy management.

Source: arXiv Generated at: 2026-06-04 00:00:00 UTC