Defaults.Exposed › October 2026 census › v10 registry › Nameserver diversity
Nameserver diversity
Methodology v10 · canonical ID nameserver-diversity · DNS (Domain Name System) Security · scored
Multiple independent nameservers so one outage doesn't take you offline.
Nameserver diversity: definition
| Canonical ID | nameserver-diversity |
|---|---|
| Category | DNS Security |
| Grade impact | Scored, counts toward the grade |
| Pass | The domain delegates to two or more nameservers with meaningful diversity. |
| Fail | A single nameserver (or no redundancy) serves the zone. |
| Example (passing) | NS: ns1.example-dns.com, ns2.example-dns.net |
Nameserver diversity across the census
98.9% of domains whose nameserver delegation could be enumerated delegate to two or more nameservers (326,097,543 of 329,604,717, as of October 12, 2026).
This check fails only on genuinely thin delegations (a single nameserver), so a high pass share is expected by construction; it does not measure provider concentration.
Aggregates only: never an individual domain's result.
How this check is scored
Nameserver diversity is one of the 24 scored checks in methodology v10. It carries points toward the grade, and a pass earns them. When the result cannot be determined for a domain (a timeout, a SERVFAIL, a redacted source), the check returns N/A and drops out of that domain's scoring denominator. A result that could not be determined is never counted as a fail; a determined absence is.
In the October 2026 census, 2,887,602 of the 332,492,319 graded domains had no determinable result for this check: the delegation has to be enumerable before the nameservers can be counted.
Every outcome in the census
| Outcome | Domains | Share of domains whose nameserver delegation could be enumerated | In the headline figure |
|---|---|---|---|
| Two or more nameservers | 326,097,543 | 98.9% | Yes |
| A single nameserver, or none enumerated | 3,507,174 | 1.06% | No |
Source: the October 2026 census rollup, deduplicated per domain, as of October 12, 2026.
Against the other checks
Among the 4 DNS Security checks with a published figure, Nameserver diversity has the 2nd highest pass share. Next above it is SOA (Start of Authority) configuration: 99.0% of domains whose SOA record could be read. Next below it is DNSSEC (Domain Name System Security Extensions): 7.03% of graded domains. Across every check with a published figure it ranks 5th of 24 .
Each share is measured on the check's own base, named on its page, so the ranking compares rates across different sets of domains.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: How to fix Nameserver setup
Cite this check
Defaults.Exposed, "Nameserver diversity (nameserver-diversity)", Grading Methodology v10 (census as of October 12, 2026). https://defaults.exposed/methodology/nameserver-diversity
Permalink: https://defaults.exposed/methodology/nameserver-diversity ·
All 33 checks: v10 registry ·
Machine-readable: /methodology/checks.json ·
Licence: open data