Can I detach the primary (eth0) network interface when the instance is running or stopped?
A.
Yes, You can.
B.
No. You cannot
C.
Depends on the state of the interface at the time
when the instance is running or stopped?
Can I detach the primary (eth0) network interface when the instance is running or stopped?
B, No
http://www.aiotestking.com/amazon/when-the-instance-is-running-or-stopped/
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html
B
http://www.aiotestking.com/amazon/when-the-instance-is-running-or-stopped/
B
Every instance in a VPC has a default network interface, called the primary network interface (eth0). You cannot detach a primary network interface from an instance.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html