Blockchain Developer's Guide

Byzantine faults

To understand PBFT and all the other consensus algorithms that come afterward, it's important to first define what a Byzantine fault is. A Byzantine fault is any event or result that would disrupt the consistency of a distributed system, such as the following:

• Failure to return any result
• Return of an incorrect or inconsistent result
• Return of a deliberately misleading result
• Any behavior that isn't defined beforehand

If any of these events happen, a Byzantine fault is said to have occurred. A Byzantine fault tolerant system is, therefore, able to handle some level of inconsistent input but still provide a correct result at the end. The key here is that such systems are fault tolerant, not fault immune. All fault tolerant ...