Smart contracts, consensus, and decentralised architecture.
6 published across 2 topics.
Solidity, re-entrancy, and EVM gas optimization.
The proxy upgradeability pattern keeps state in the proxy and delegates calls to replaceable implementation logic, which makes storage layout, initializers and upgrade admin control the core smart contract security risks. Use this solidity answer to show the decision, trade-off, and evidence rather than a memorised definition.
A reentrancy attack happens when a smart contract calls an untrusted address before updating its own state, letting the callee enter again and reuse stale balances. The checks-effects-interactions pattern closes that window by validating first, mutating state next and calling out last.
Solidity storage layout dominates gas cost because persistent 32-byte slots are expensive to read and write on every node. Efficient smart contracts pack fields, cache repeated storage reads, avoid unnecessary writes and preserve layout during upgrades.
Wallets, RPC nodes, and decentralized storage.
A wallet transaction signing flow chooses nonce and fee fields, encodes the transaction, signs the hash locally with the private key and sends only the signed transaction to an RPC node for mempool broadcast. Use this wallets answer to show the decision, trade-off, and evidence rather than a memorised definition. It also connects transactions to the point an interviewer is testing.
dApp RPC node reliability means treating blockchain nodes as rate-limited, sometimes lagging read replicas rather than perfect infrastructure. Production backends need retries, confirmation depth, bounded log queries, nonce coordination and their own indexed reads.
Decentralized storage is the right choice when content-addressed bytes must be independently verifiable and durable beyond one operator. A database is better for mutable records, access control, deletion, secondary indexes and low-latency queries.