SSL & DNS Security

DNS Monitoring 101: Preventing Outages Before Customers Notice

From misconfigurations to propagation, glue records, and failover—what to watch and how to alert.

Published 02 Oct 2025

DNS is the front door to every web request. Small mistakes—wrong TTLs, missing glue, or stale records—can cause outages that look like application failures. This guide outlines practical DNS monitoring for SMBs.

Related: SSL Guide · 5 Common DNS Misconfigurations · Uptime Guide

What to monitor

  • NS records: delegation health and consistency
  • A/AAAA: expected targets, no stale entries
  • CNAME: chain length and resolution
  • MX/TXT: email deliverability dependencies
  • SOA: serial increments post‑change
  • Reverse lookups when applicable

TTLs and propagation

Use shorter TTLs during migrations, longer once stable. Monitor that changes propagate to all authoritative servers.

Alerting

  • Critical record drift (A/AAAA, CNAME on key hosts)
  • Delegation breakage
  • Unexpected removal of MX/TXT

Feature: DNS Monitoring. Pair with SSL monitoring for end‑to‑end coverage.

Put this into practice

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