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23/06/2026 7:15 pm
TL;DR: DNS outages can make websites, apps, email, and internal tools unreachable even when servers are still running, according to DigiCert. Misconfigurations, maintenance errors, data-centre issues, and propagation delays show that DNS resilience is now an availability and governance problem, not just an infrastructure one.
NHIMG editorial — based on content published by DigiCert: DNS Outage: What Is It and Why You Want to Avoid It
By the numbers:
- The article notes that a high TTL like 24 hours can extend the impact of a DNS problem.
Questions worth separating out
Q: How should security teams reduce the impact of a DNS outage?
A: Security teams should treat DNS as a dependency layer with explicit ownership, change control, and failover testing.
Q: Why do DNS outages affect more than websites?
A: DNS supports email routing, application discovery, internal tooling, and many identity flows that users never see directly.
Q: What usually causes DNS outages in production environments?
A: The most common causes are maintenance mistakes, misconfigured records, data centre problems, and propagation delays.
Practitioner guidance
- Audit critical DNS dependencies Map which authentication, email, application, and internal service paths depend on each authoritative zone and recursive resolver chain.
- Stage DNS changes with validation gates Require record review, syntax checks, and rollback steps before editing zone files or pushing automated updates.
- Test failover under real resolver conditions Exercise authoritative failover, low-TTL propagation, and backup endpoint health checks in a controlled drill.
What's in the full article
DigiCert's full blog covers the operational detail this post intentionally leaves for the source:
- Step-by-step explanations of authoritative name server maintenance and how sequencing affects availability
- Examples of DNS record types such as A, AAAA, CNAME, MX, and TXT in outage scenarios
- Operational detail on DNS failover monitoring and how low TTL values change recovery speed
- Practical examples of how propagation delay affects users in different regions
👉 Read DigiCert's analysis of DNS outage causes, impact, and failover →
DNS outage risk: is your resilience model actually enough?
Explore further
25/06/2026 3:11 am
DNS resilience is a hidden identity control problem, not just an uptime problem. DNS sits underneath authentication, collaboration, service discovery, and workload access, so a lookup failure can break the path to both human and non-human identities. That makes DNS governance part of the access stack, even when security teams treat it as pure infrastructure. Practitioners should assess DNS alongside other dependency controls, not after availability has already collapsed.
A few things that frame the scale:
- The average estimated time to remediate a leaked secret is 27 days, despite 75% of organisations expressing strong confidence in their secrets management capabilities, according to The State of Secrets in AppSec.
- 43% of security professionals are concerned about AI systems learning and reproducing sensitive information patterns from codebases, according to the same report.
A question worth separating out:
Q: How do organisations know if DNS failover is actually working?
A: They should test whether queries move to the backup endpoint from multiple resolvers, whether the backup remains healthy under load, and whether cached records expire quickly enough to reflect the change. A failover plan is only effective if users can reach the alternate path before the outage becomes widespread.
👉 Read our full editorial: DNS outage risk shows why resilience needs more than uptime
