If two instances cummunicate with public ip address, either
- Traffic between EC2 instances in
- different AWS Regions stays within the AWS network
- if there is an Inter-Region VPC Peering connection between the VPCs where the two instances reside.
- Traffic between EC2 instances in
- different AWS Regions where
- there is no Inter-Region VPC Peering connection between the VPCs where these instances reside,
- is not guaranteed to stay within the AWS network.
- Traffic between two EC2 instances in the same AWS Region stays within the AWS network, even when it goes over public IP addresses.
- AWS does some networking hacks to do this, so that it may be fast
Same region = stays within aws both public and private Different region = stays may/may not if inter region connection is there