<p>Registers the specified targets with the specified target group.</p> <p>If the target is an EC2 instance, it must be in the <code>running</code> state when you register it.</p> <p>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.</p> <p>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.</p>

{
  "success": true,
  "data": {
    "id": "abc123",
    "created_at": "2025-01-01T00:00:00Z"
  }
}

{
  "success": false,
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid request parameters"
  }
}