The market went wild. Robinhood's DNS went down.

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Markets are going wild. You open your trading app. You can't buy. You can't sell. You can't even cancel. And support? Disrupted too. No phone line.

2 and 3 March 2020. Robinhood's app and website shut down. FINRA counts 12 point 5 million accounts. Every customer, locked out. Record trading volume. Record sign-ups. Historic volatility.

The load stresses Robinhood's infrastructure. It struggles. Then a thundering herd. A crowd of requests, all at once. And here's the villain. It takes down DNS. DNS tells every system where the others live. Without it, the cascade.

This wasn't just annoying. FINRA found it cost money. Buys that never went through. Stop-loss orders that didn't fire. Options that expired worthless. Some lost tens of thousands of dollars.

But here's the catch. Robinhood did monitor capacity. The regulator found it didn't plan for its growth. Or extreme markets.

June 2021. The regulator FINRA fines Robinhood 57 million dollars. Plus about 12 point 6 million in restitution. For the outages and other failings.

Your busiest day is the day you can't afford to fall over. Plan capacity for the worst day. And guard quiet shared services, like DNS.

Full story in the article.