Two nameservers cut DNS query repeats by 25% in APNIC test

APNIC researchers have observed that domains served by two authoritative nameservers experience significantly fewer repeated DNS queries than those relying on a single nameserver. The finding emerged from a large-scale measurement conducted in August 2026, which analyzed resolver behavior across millions of unique DNS queries to assess the impact of nameserver count on query repetition rates.

What the test revealed

The experiment, conducted between 5 and 11 August 2026, tasked recursive resolvers with resolving unique domain names to avoid caching effects. Researchers divided the global DNS traffic into six geographic zones—North America, South America, Europe and Africa, India, Asia, and China—each served by a single authoritative nameserver. The nameservers were dual-stack, supporting both IPv4 and IPv6.

When a single nameserver was used, 58% of test cases completed with just one query. However, when a second nameserver was added, the single-query success rate rose to 71%. The average number of queries per test dropped from 3.43 to 2.57, while the average number of repeat queries fell from 3.8 to 2.6. This outcome contradicted expectations, as researchers had anticipated that additional nameservers might increase query repetition due to resolvers querying multiple authoritative sources for consistency.

Timing and resolver behavior

The reduction in repeat queries was most pronounced in the first second of resolution. With a single nameserver, 85% of duplicate queries arrived within that window, compared to 75% with two nameservers. The distribution of repeats also shifted: a single nameserver saw local peaks at 100ms, 310ms, and 800ms, while two nameservers introduced additional peaks at 50ms, 370ms, and 750ms.

Notably, 17% of repeated queries occurred within 10ms of the initial query when using a single nameserver, a pattern that dropped to 12% with two nameservers. This rapid-fire duplication suggests the involvement of resolver farms—front-end dispatchers that distribute queries across multiple backend resolvers. Such setups, common among large consumer ISPs, may explain the observed behavior, as the front-end systems could be duplicating queries to improve resolution speed or resilience when only one authoritative nameserver is available.

Why the results matter

The findings challenge conventional assumptions about DNS redundancy. While multiple nameservers are typically deployed for fault tolerance, the APNIC test suggests they may also reduce unnecessary query load on recursive resolvers. This could have practical implications for DNS operators, particularly those managing high-traffic zones or relying on resolver farms.

The study did not provide a definitive explanation for the observed behavior, as DNS query handling remains relatively opaque. However, the data reinforces the operational advice of using at least two nameservers to serve a zone, not only for resilience but also to optimize resolver performance.