Building a Fast Domain Search Architecture (RDAP + DNS + WHOIS)

Delivering sub-200ms perceived latency for bulk domain availability requires layering protocols, caching, and progressive disclosure. This post breaks down the system powering our search.

Goals

• Instant feedback (<150ms first paint)
• High accuracy (minimize false "available")
• Cost-efficient (no paid APIs)
• Extensible pricing enrichment

Layer Stack

1. RDAP Quick Hint – 100–140ms timeout, first authoritative attempt.
2. RDAP Consensus – Multi-endpoint longer window for definitive status + metadata (dates, statuses).
3. DNS Delegation Check – SOA/NS/A tri-probe to override false availables.
4. WHOIS Fallback – Bulk port-43 for non-definitive "available" responses.
5. Price Enrichment – Async registrar adapters (Porkbun, Gandi, more coming).
6. Streaming NDJSON – Incremental delivery: availability → corrections → prices.

Event Types

Accuracy Tactics

• Parallelized RDAP with fastest-wins + consensus
• DNS tri-type verification (SOA/NS/A) cached 30m
• WHOIS only for ambiguous availables
• RDAP dates (created, updated, expires) surfaced to UI
• Premium heuristic (price threshold) styling

Caching Windows

Streaming UX

• Sort available first, then alphabetical.
• Corrections merge seamlessly (stateful map keyed by domain).
• Prices slot in without reordering unless availability changed.

Future Enhancements

• Confidence scoring badge
• Multi-DoH resolver cross-check
• Expiry countdown tooltips
• Bulk export & API key tier
• Registrar coverage expansion (Namecheap, GoDaddy public offer scraping)

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Want a deep dive into WHOIS parsing heuristics next? Let us know.