Which statement about the External Time Reference Network (ETRN) is NOT true?

The External Time Reference Network (ETRN) plays a critical role in maintaining synchronization across various systems and operations that rely on precise timing. The assertion that the network will always have a time quality (QT) of 15 is not accurate. Time quality is a measure that indicates the reliability and accuracy of the timing information, and it can vary based on several factors such as network conditions and the quality of the time sources. Therefore, it is not guaranteed to consistently reflect a QT of 15, making this statement untrue.

In contrast, the other statements accurately describe the characteristics of ETRN. The network does maintain synchronization with regular updates, ensuring that all connected systems receive current timing data to function effectively. Additionally, ETRN is designed to support multiple time sources, allowing for flexibility and resilience in timekeeping. Finally, the capability to allow for temporal adjustments based on network needs is essential for accommodating various operational scenarios and maintaining optimal performance across systems.