Is my understanding correct about how AWS charges Data Transfer IN via public IP

Question

As stated here [on demand pricing](https://aws.amazon.com/ec2/pricing/on-demand/),  AWS does not charge for all `Data Transfer IN To Amazon EC2 From Internet`, however, it will charge for Data Trasnsfer **IN** Amazon EC2 From public IP address within the same AWS Region.
```
Data transferred "in" to and "out" from Amazon EC2, Amazon RDS, Amazon Redshift, 
Amazon DynamoDB Accelerator (DAX), and Amazon ElastiCache instances, Elastic Network 
Interfaces or VPC Peering connections across Availability Zones in the same AWS Region 
is charged at $0.01/GB in each direction.

IPv4: Data transferred "in" to and "out" from public or Elastic IPv4 address is 
charged at $0.01/GB in each direction.

IPv6: Data transferred "in" to and "out" from an IPv6 address in a different VPC is 
charged at $0.01/GB in each direction.
```

I am trying to subscribe to Binance market data with an AWS EC2. Assume that the Binance server and my EC2 are within the same `Availability Zones`, in this case, I have to subscribe to Binance via public `IP`, so I will be charged at $0.01/GB for subscribed data if my understanding is correct.

I am confused because, according to my understanding, it would be free **IF** the Binance server is not in AWS but somewhere else. It is counter-intuitive.

Is my understanding correct about this? It will be helpful if anyone has ideas to reduce bandwidth costs when subscribing to the Binance server.

Thanks for spending time on this.

BSONIKA · Accepted Answer

Your understanding is true on your server and Binance server communicating using Public IP is charged at $0.01 in both directions. While any Traffic IN from Internet is free, 2 EC2 communicating over Public IP doesn't get routed via internet, it takes AWS's private network. Refer: Billing section under https://aws.amazon.com/vpc/faqs/.

Now to answer your question on how can you optimize, getting 2 EC2 to communicate via Public IP is anti-pattern. You must use Private IP (again both EC2 should be in same AZ, to avoid inter-AZ charges). In your use case you may not be able to use Private IP. So, I really don't see any option to optimize further.

re:Post Agent · Answer

Your understanding is partially correct, but there are some important clarifications to make:

1. Data Transfer IN from the internet to Amazon EC2 is generally free. This includes data coming from external sources like Binance, regardless of whether they are hosted on AWS or not.

2. The charges you're referring to for data transfer "in" and "out" using public or Elastic IPv4 addresses within the same AWS Region apply to traffic between AWS resources, not traffic from the internet.

3. In your scenario with Binance, assuming their servers are not part of your AWS infrastructure:
   - If you're subscribing to Binance market data from the internet, the incoming data to your EC2 instance would be free.
   - You would only incur charges for any data you send out to the internet or between different Availability Zones within AWS.

4. The $0.01/GB charge for data transfer between Availability Zones in the same region applies when you're transferring data between your own resources in different AZs, not for incoming internet traffic.

5. IPv6 data transfer charges only apply when transferring between different VPCs, not for internet traffic.

To reduce bandwidth costs when subscribing to the Binance server:

1. Ensure your EC2 instance is in the most appropriate region to minimize latency and potential cross-region data transfer charges.
2. If possible, use a single EC2 instance to receive and process the data, avoiding unnecessary internal data transfers.
3. Be mindful of any outbound data you might be sending, as that would incur charges.

Remember, while inbound data from the internet is generally free, you should always monitor your usage and costs to avoid any unexpected charges.  
**Sources**  
[Regional data transfer charges | AWS re:Post](https://repost.aws/questions/QUULkzp8j9SVq3WZZe0uGatg/regional-data-transfer-charges)  
[Community | Optimizing Network Traffic and Cost in AWS During Migration](https://community.aws/content/2fdHdKYvkBVCx7Y2VymX0FpKtpg/optimizing-network-traffic-and-cost-in-aws-during-migration)  
[Can someone explain data transfer charges in detail? | AWS re:Post](https://repost.aws/questions/QUvmFGqjHnR8-N4016gMWaLw/can-someone-explain-data-transfer-charges-in-detail)

Is my understanding correct about how AWS charges Data Transfer IN via public IP

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