If you are calling an AWS Elastic Load Balancer (ELB) from an AWS EC2 instance within the same region, then typically the traffic between the two services will stay within the AWS network and not be charged for Internet data transfer fees. AWS generally does not charge for data transfer between services within the same region, as long as the traffic stays within the AWS network.
If your EC2 instance and ELB are in the same region, and you are using the public DNS of the ELB to communicate with it, then the traffic between the two will still be routed through the AWS network, and you will not be charged for Internet data transfer fees.
Setting up a VPC between the EC2 client and AWS ELB can further ensure that all traffic stays within the AWS network and help you save on public internet traffic, but it may not be necessary if you are already using the public DNS of the ELB from within the same region.
It's important to note that there may be other factors that could affect your AWS charges, such as the amount of data transferred and the specific AWS services you are using. You should consult the AWS documentation or contact AWS support if you have specific questions about your usage and potential costs.
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