Why Is Transaction Ordering a Greater Challenge for Front-Running on a DEX than a CEX?

On a CEX, the exchange maintains a private, centralized order book and controls the exact sequence of trade execution, typically following a strict price-time priority rule. This eliminates the external opportunity for front-running.

On a DEX, transactions are broadcast to a public mempool and their final ordering is determined by decentralized, self-interested validators or miners. These actors can prioritize transactions based on higher gas fees, allowing a front-runner to pay more to jump the queue, making transaction ordering a fundamental challenge for fairness.