A Distributed Denial of Service (DDoS) attack against a blockchain involves an attacker overloading the network with a higher number of requests, connections, or transactions than it can handle. This results in congestion and can cause users to be unable to access the network until the attack ceases. Blockchains do possess some resistance to these attacks due to the network's ability to survive node failures. Furthermore, transaction fees on most public blockchains make it costly for attackers to initiate and sustain transaction flooding attacks. Despite these measures, DDoS attacks can still pose a significant threat to blockchain networks. Therefore, blockchain developers and operators must continue to implement appropriate security measures to protect their networks against such attacks. These measures may include implementing bandwidth limits, rate limiting, and filtering rules, among others, to prevent the network from being overwhelmed and to maintain its integrity.