Registers the specified targets with the specified target group.

If the target is an EC2 instance, it must be in the running state when you register it.

By default, the load balancer routes requests to registered targets using the protocol and port for the target group. Alternatively, you can override the port for a target when you register it. You can register each EC2 instance or IP address with the same target group multiple times using different ports.

With a Network Load Balancer, you cannot register instances by instance ID if they have the following instance types: C1, CC1, CC2, CG1, CG2, CR1, CS1, G1, G2, HI1, HS1, M1, M2, M3, and T1. You can register instances of these types by IP address.