DNS Resilience Assessment

The DENIC incident of 5 May 2026 lasted just under two hours. It hit organisations without warning, affected domains without a common operator or hoster, and could not be fixed by the affected organisations themselves. For many it was the first encounter with the structural fragility of their DNS dependencies.

The DNS Resilience Assessment is aimed at organisations that want to know not only whether DNS is configured securely but also whether their overall infrastructure would withstand a real DNS outage. It can be delivered as a stand-alone project or as the third stage of a complete DNS project, building on the findings of the DNS Security Audit and the DNS Architecture Review.

We simulate concrete DNS failure scenarios for your infrastructure: what happens if the primary resolver fails? What if the registrar or the authoritative nameserver operator has an outage – as during the DENIC incident? What if a DNSSEC key rotation goes wrong?

For each scenario we evaluate the expected impact on your services, your customers and your internal processes. The result is a realistic business impact picture – not a theoretical risk matrix. The analysis is structured and does not involve destructive testing.

Who are your DNS dependencies? Registrar, authoritative nameserver operator, resolver, CDN with DNS function, cloud DNS services? For each of these third parties we assess: is there an SLA? Is there a defined escalation procedure? Is there an alternative in case of a prolonged outage?

Third-party DNS dependencies without documented failure procedures are one of the most frequent findings – and in the context of DORA a direct topic for ICT third-party risk management.

An outage that is noticed only after 45 minutes is more severe for most organisations than one that is detected in 90 seconds. We assess how quickly your current monitoring would realistically detect a DNS outage – and where the gaps lie between DNS monitoring, SIEM and incident response.

For NIS2-regulated organisations this assessment is directly relevant to meeting reporting deadlines.

The assessment ends with a prioritised roadmap. Short-term measures include TTL optimisation, monitoring setup and documenting escalation paths. Medium-term actions focus on resolver redundancy, DNSSEC monitoring and SIEM integration. Long-term, the roadmap addresses topics such as multi-provider strategies and regular resilience tests.

The roadmap is prioritised by effort and impact – not a wish list but an actionable plan that fits your capacity.

Resilience against DNS outages is a direct or derived requirement in several regulatory frameworks. The following positioning is a technical assessment and does not replace legal advice.

NIS2 requires affected organisations to take measures to ensure business continuity during security incidents (Art. 21 NIS2). A DNS outage – whether self-inflicted, caused by third parties or by upstream infrastructure – can be such an incident. NIS2 also requires reporting of significant security incidents within defined deadlines (24-hour early warning, 72-hour full report). This requires the incident to be detected – which presupposes working DNS monitoring.

DORA puts DNS resilience directly in the context of ICT risk management and operational resilience. Art. 11 DORA requires business continuity measures for critical ICT systems and dependencies. DNS is such a dependency. Art. 26 DORA foresees Threat-Led Penetration Tests (TLPT) for significant financial undertakings, which can also include DNS failure scenarios.

The TKG security concept under §166 TKG must include measures to ensure the availability and integrity of communications networks. For telecommunications operators, DNS resilience is therefore part of the security concept requirements.

Manufacturers of connected products that rely on DNS-dependent services (updates, telemetry, cloud connectivity) should ensure under Security by Design and Vulnerability Management that known failure risks are addressed. The assessment identifies product-specific DNS risks.

1. Kick-off – Clarify scope, target infrastructure and existing documentation. Free of charge, approx. 45 minutes, remote.

2. Technical data collection – Combination of technical queries, questionnaire and, if useful, workshop elements with IT stakeholders. Remote or hybrid.

3. Scenario simulation – Structured walk-through of concrete failure scenarios for your infrastructure. No destructive tests; the analysis is based on the architecture data.

4. Assessment report – Business impact evaluation, dependency analysis, monitoring gap assessment, regulatory positioning.

5. Action roadmap – Prioritised plan with short-, mid- and long-term measures.

6. Closing presentation – Results review with IT leadership and, where appropriate, executive management. Remote or on site.