Earnestlink
Practical engineering writing for people who keep systems alive.
Structuring DNS for Reliability
July 18, 2026
Domain resolution outages produce an awkward paradox: server instances remain perfectly healthy while clients perceive complete downtime. Insulating against platform-level registrar outages demands secondary authoritative DNS providers operating over separate routing infrastructure.
Configuring record expiration windows involves competing operational goals. Low TTL values promise rapid agility but multiply resolver query rates and propagate minor transit anomalies; high values cushion against upstream downtime while locking migrations in place. A tiered configuration assigning low TTLs to failover routes and long durations to invariant records performs best.
Cache Invalidation Patterns That Survive Traffic
April 30, 2026
Engineers constantly repeat the classic computer science joke about cache invalidation, yet few design caches resilient to thundering herds. Request coalescing remains the critical design pattern: upon key expiration, an isolated worker fetches fresh data while concurrent requests receive stale reco…
Multi-Region Failover Planning
May 31, 2026
Multi-region failover is mostly decided before the incident. The two questions that matter - how fresh does the standby data need to be, and who is allowed to press the button - sound managerial, but they drive every technical choice downstream from replication topology to health-check placement.…
A Practical Guide to API Rate Limiting
July 5, 2026
Rate limiting is one of those features everyone agrees is important and almost nobody designs deliberately. The naive per-IP token bucket works until you meet carrier-grade NAT, where a hundred thousand mobile users share a handful of addresses and your limiter punishes them as a single entity.…
Reading Latency Percentiles Without Fooling Yourself
April 26, 2026
Arithmetic averages hide the extreme tail latencies that percentiles make evident. Even if an endpoint posts an average duration of fifty milliseconds, one out of twenty calls might experience a grueling two-second delay; customers subjected to cold paths and overloaded database shards are the ones …
More reading
- HTTP/3 and QUIC: What Changed for Operators — Networking, August 12, 2026
- Zero-Downtime Deployments Without the Drama — Operations, June 27, 2026
- When to Choose a Queue Over a Request — Engineering, June 13, 2026
About us
Founded by former SREs and network engineers, our editorial desk focuses on the practical side of operating distributed services - less hype, more packet captures.