Defaults.Exposed › Methodology › v7 registry › TLS compression
TLS compression
Methodology v7 · canonical ID tls-compression · TLS & Certificates · informational · census as of July 28, 2026
Compression disabled to avoid a known attack class (CRIME).
Definition
| Canonical ID | tls-compression |
|---|---|
| Category | TLS & Certificates |
| Grade impact | Informational — never moves the grade |
| Pass | TLS-level compression is disabled. |
| Fail | TLS compression is enabled. |
| Example (passing) | Compression: NONE |
No-data rule: when this check couldn't be determined for a domain (timeout, SERVFAIL, redacted
source) it returns N/A and is excluded from that domain's scoring denominator — "couldn't determine"
is never counted as a failure. "Determined absent" is a real fail.
Prevalence across the census
The public census rollup does not publish a per-check figure for tls-compression (as of July 28, 2026).
Whole-census aggregates live at /data; no number is shown here rather than an estimated one.
Census denominator: 275,666,275 graded domains. Aggregates only — never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/en/fix/tls
Cite this check
Defaults.Exposed, "TLS compression (tls-compression)", Grading Methodology v7 (census as of July 28, 2026). https://defaults.exposed/methodology/v7/tls-compression
Permalink: https://defaults.exposed/methodology/v7/tls-compression ·
All 34 checks: v7 registry ·
Machine-readable: checks.json ·
Licence: open data