Describe what a brute-force attack entails.

A brute-force attack involves systematically trying every possible combination of passwords or encryption keys until the correct one is found. This method relies on the computational power available to attempt numerous combinations in a relatively short period, making it a straightforward yet often effective way to compromise accounts if proper security measures are not in place. The attacker may use automated tools to accelerate this process, allowing them to test hundreds or thousands of potential passwords per second.

In contrast, other methods mentioned involve different forms of attack. Network congestion and denial-of-service attacks focus on overwhelming services to disrupt availability rather than gaining access, while encryption for ransom refers to malware tactics aimed at extorting money rather than compromising passwords through guesswork. Therefore, the definition of a brute-force attack specifically aligns with exhaustive password or encryption key guessing, which directly pertains to the integrity and confidentiality of accounts.