Why Nginx Caches DNS for Weeks and How to Fix It

In production, Nginx cached DNS lookups for up to a month, causing requests to stale IPs after CDN changes; this article explains the root cause, demonstrates how to configure upstream health checks and the built‑in resolver to ensure timely DNS updates and avoid prolonged outages.

DNSOperationsload balancing

0 likes · 6 min read

Why Nginx Caches DNS for Weeks and How to Fix It

MaGe Linux Operations

Nov 25, 2023 · Fundamentals

How DNS Caching, Recursion, and Iteration Really Work

This article explains the DNS caching strategy, the difference between recursive and iterative queries, and how resolvers and authoritative servers cooperate to translate hostnames into IP addresses while optimizing network resources.

DNSRecursioncaching

0 likes · 4 min read

How DNS Caching, Recursion, and Iteration Really Work

Hujiang Technology

Jun 29, 2017 · Operations

Understanding DNS Resolver Caching Issues in Salt-Minion and glibc res_init() Behavior

The article explains how salt‑minion’s DNS resolution can become stale after a data‑center migration because each Linux process caches resolver settings in a private _res structure initialized by glibc’s res_init(), and it offers practical ways to force a refresh or redesign the lookup mechanism.

DNSLinuxOperations

0 likes · 8 min read

Understanding DNS Resolver Caching Issues in Salt-Minion and glibc res_init() Behavior