When calculating pricing for ECS on https://calculator.aws/#/createCalculator there is a distinction between the pricing of inbound and outbound traffic. I am confused about what the precise difference between those two is.
For instance, let's imagine two roughly identical ec2 instances. They are identical except that they both have a different cronjob on them.
Instance A makes a REST request to a public endpoint every hour and receives a 1 KB payload as a response every time.
Instance B makes a REST request to the same public endpoint every hour with a different parameter and receives a 1 GB download as a response.
The two things I can see happening based on the information provided by Amazon are:
- Both get basically the same quantity billed for Outbound Data Transfer but Instance B gets a significantly larger quantity under "Inbound".
- Instance B has a high quantity under Outbound Data Transfer because the responses are considered part of the outbound request.
An auxiliary question is this: if the above assumes TCP, will the answer be consistent over UDP?