The benefits of serving stale DNS entries when using Consul

The text discusses a solution for reducing DNS query latencies using Consul and Unbound. The problem arises due to long latencies when resolving names in certain parts of the world, especially with DNS over TLS and low TTLs. To address this issue, prefetching and stale cache strategies are explored. Prefetching refreshes DNS records before they expire but is not effective for infrequently accessed records or those with small TTLs. Stale cache serves expired records from the cache while dispatching a job to refresh the record in the background, which helps improve latency and resiliency. The text also covers test configurations, results, and future improvements for this solution.