What Is a ‘Denial-of-Service’ (DoS) Attack in the Context of a Blockchain Network?

A Denial-of-Service (DoS) attack on a blockchain network aims to make the network unusable or severely degrade its performance for legitimate users. In a blockchain context, this is typically achieved by flooding the network with a massive volume of transactions, known as transaction spam.

The goal is to fill the mempool and all available block space, driving up transaction fees and confirmation times. While a successful DoS attack does not compromise the security of past transactions, it effectively halts or severely limits the network's ability to process new ones.