What is external synchronization in distributed system?

External synchronization in a distributed system refers to the coordination and timing of operations across different nodes or components to ensure consistency and coherence of data. It typically involves mechanisms like clocks, timestamps, or consensus algorithms to align the states of distributed processes. This is crucial for maintaining data integrity when multiple nodes may access or modify shared resources simultaneously. External synchronization helps prevent issues such as race conditions and ensures that events are perceived in a consistent order by all participants in the system.