Can you change the security groups associated with the primary network interface (eth0) of an EC2 instance running inside a VPC?
Yes
Only if the instance is stopped
Only when the instance is launched
No
Explanations:
You can change the security groups associated with the primary network interface (eth0) of an EC2 instance while the instance is running.
The instance does not need to be stopped to modify the security groups of the primary network interface.
You can change the security groups at any time, not only when the instance is launched.
You can modify the security groups associated with the primary network interface; it’s not restricted.
I draft that the answer is:
Yes