GFW DNS filtering effectiveness shows diurnal variation: correct response rates are lowest in the early morning hours (before 6:00 a.m.) and rise throughout the day, suggesting filtering devices fail to process all DNS queries during peak traffic periods. However, the overall variance across time is small — maximum standard deviation of 0.03 — indicating the filtering mechanism is broadly stable over the 40-day measurement window.
From 2022-cheng-in-depth — In-Depth Evaluation of the Impact of National-Level DNS Filtering on DNS Resolvers over Space and Time
· §4.3, Figure 11
· 2022
· Electronics
Implications
Circumvention tools that rely on DNS-based bootstrapping may have marginally higher success rates during high-traffic periods when GFW filtering devices are overloaded, but the gain is small (<3% std dev) and not a reliable bypass strategy.
Monitoring-based adaptive retry (retrying DNS resolution during predicted peak hours) is unlikely to yield significant improvement and should not be prioritized over structural bypasses like encrypted DNS.