System designHardsd-g129

Subject ReconciliationLevel Senior–Staff~50 minCommon in Databases & SQL interviewsIndustries Technology

Question

Design a continuous internal-consistency reconciliation system for a crypto exchange that must prove, on an ongoing basis, that internal user balances (the exchange's ledger) match actual on-chain + custodial holdings, across ~20 assets and millions of accounts. Deposits/withdrawals settle on-chain with confirmation delays and reorgs. The system must detect any drift (a user credited but funds not actually received, or holdings unaccounted for) quickly. Describe the architecture and how you handle blockchain-specific consistency hazards.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

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