Internet facing or Internal load balancer

ELB can be Internet facing or Internal load balancer so let us have a quick look on both of this types.

                                                                     Internet facing:

• ELB nodes will have public IP address.
• DNS will resolve the ELB DNS name to these IP address.
• It routes traffic to the private IP address of your registered EC2 instances.
• Hence EC2 instance do not need to have public IP address.
• You need on “Public” subnet in each AZ where the internet facing ELB will be defined, such that the ELB will be able to route internet traffic.
• Define this subnet in the ELB configuration.

                   

Internal load balancer:

• ELB nodes will have Private IP address to which the DNS resolves ELB DNS name.
• It routes traffic to the private IP address of your registered EC2 instances.
• Format of the ELB DNS name of internal ELB
• Internal-name-123456789.region.elb.amazonaws.com