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Code RoomAuthoritative DNS under DDoS
HardPrep Room Coding #2457

Authoritative DNS under DDoS

On-callSecurityStorage & CDNSenior–Staff~40 min

At 15:40 your public site becomes unreachable for a large fraction of users worldwide, while a smaller fraction load it fine. Dashboards: your origin and CDN edges are healthy and lightly loaded — almost no traffic is arriving at all. Synthetic checks from several regions fail at the DNS-resolution step ('SERVFAIL'). Your authoritative DNS is hosted by a single managed DNS provider, and that provider's status page reports it is mitigating a large DDoS against its anycast network. Recent context: none on your side; no deploy. How do you triage and mitigate?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

0:00 of about 40 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.