Why it is recommended to create region specific subnet

Summary

Why it is recommended to create region specific subnet

Content

Hello experts,

I was trying to create below setup.

A primary and standby database in same vcn but with different availability domain and using different subnet.

Question popped in my mind is whether I should choose region or ad specific subnet.

What is the real use case for choosing subnet as region specific.

 

Regards

Dhritiman Deb