How many SADR are installed onboard?

The correct answer indicates that there are two System Architecture Data Repository (SADR) installed onboard. Having two SADRs ensures redundancy and availability, which are critical in network security contexts. If one SADR were to fail or become compromised, the other would still be operational, allowing continued access to vital data and ensuring that the system remains functional and secure.

In many systems, having a backup repository is essential for maintaining data integrity and enabling rapid recovery in case of failure. This is especially true in environments where data accuracy and uptime are paramount. The use of two SADRs is a common practice in network architecture design, as it not only enhances reliability but also facilitates load balancing, where data requests can be distributed between both repositories, improving performance overall.

While other quantities may seem plausible, they do not align with the standard operational design typically implemented for SADRs, which often prioritizes redundancy and reliability over having a more extensive number of repositories that may complicate management and maintenance.