FAQ

February 17, 2026 ยท View on GitHub

Why does a domain show as UNKNOWN?

UNKNOWN typically means the check could not be completed reliably, for example:

  • timeout
  • temporary network issues
  • registry response differences
  • parsing limitations on specific WHOIS servers

Try again with:

domain-check example.com --debug

For automation, treat UNKNOWN as retryable unless your policy says otherwise.

RDAP vs WHOIS: which result is authoritative?

domain-check is RDAP-first and uses WHOIS as fallback.

  • RDAP is structured and generally easier to parse correctly.
  • WHOIS is less standardized and varies by registry.

In borderline cases, retry and validate against registry-native tools if needed.

What does --no-bootstrap do?

It disables IANA bootstrap discovery and restricts checks to hardcoded TLD support. Use it for:

  • offline or constrained environments
  • deterministic behavior where external bootstrap fetch is undesired

Why is docs.rs showing an older version than the repository?

docs.rs reflects published crate versions, not unreleased main branch changes. Use the repository docs for latest in-progress behavior, and docs.rs for latest published release behavior.

How do I avoid interactive prompts in CI?

Use non-interactive-friendly flags:

domain-check --file domains.txt --batch --json --yes

Non-TTY environments already avoid confirmation prompts, but explicit flags are safer for reproducibility.

JSON or CSV for automation?

  • Use JSON when you need full metadata and robust parsing.
  • Use CSV for lightweight spreadsheet/report pipelines.

If schema stability matters, pin tool version and validate expected fields in your pipeline.

How can I speed up large checks?

  • Increase concurrency (--concurrency 25 to --concurrency 75, based on environment).
  • Use --streaming for early results on long runs.
  • Use --batch --json for stable downstream processing.
  • Use presets to avoid unnecessary TLD scope expansion.

Can I use this as a Rust library?

Yes. Use domain-check-lib for direct integration:

  • batch checks
  • streaming checks
  • config-driven behavior
  • domain generation and expansion helpers

See: domain-check-lib/README.md.