HLD-120·Caching & Edge
Easy · 500 ptsGlobal Anycast Authoritative DNS & Zone Store
Design a Route 53 / Cloudflare-style authoritative DNS lookup and zone-record propagation backend serving ultra-low-latency A/AAAA/CNAME answers.
Max p99
≤ 25 ms
Availability
≥ 99.5%
Budget
≤ $2,400
Functional Requirements
- FR-1GET /dns/resolve?name={domain_name} — Returns authoritative DNS record set with TTL.
- FR-2POST /dns/zones/{zone_id}/records — Updates DNS records and propagates to edge POPs.
- FR-3PATCH & DELETE /dns/resolve/{zone_id} — Updates, revokes, or deletes zone_id entries with bounded TTL or explicit cache/index invalidation.
- FR-4DNS resolution must sustain 99.5%+ availability during origin zone-store node failure.
Workload Profile
Baseline Queries30,000 Query RPS / 400 Zone Edit RPS
DDoS & Failover Surge78,000 Query RPS / 1,200 Write RPS
Active Working Set8 GB active zone records
Traffic DistributionExtreme skew on flagship domain_name records
Consistency Model
Eventual global POP propagation (< 10s) governed by record TTL; zone edits durably persisted.
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