When adding secondary VNICs, what is a requirement regarding availability domains?

In Oracle Cloud Infrastructure (OCI), when you are adding secondary Virtual Network Interface Cards (VNICs) to a Compute instance, it is essential that both the primary and secondary VNICs are located within the same Availability Domain (AD). This requirement ensures that the VNICs can communicate efficiently without the added complexity of cross-domain networking.

Having both VNICs in the same AD helps maintain low latency and high throughput by keeping them within the same infrastructure environment, allowing for better performance and easier management. It also simplifies the networking configuration since resources within the same AD can communicate with lower overhead.

While secondary VNICs can offer flexibility in networking setups, the stipulation to keep them within the same Availability Domain is a crucial aspect of OCI's design, enabling smoother operations and resource management.