What happens to the previous association of a subnet when it is associated with a new Access Control List (ACL)?

When a subnet is associated with a new Access Control List (ACL), the previous association with any existing ACL is removed. In AWS, each subnet is allowed to be associated with only one ACL at a time. When you make a new association with a different ACL, the previous ACL that was associated with the subnet is effectively disassociated or removed. This ensures that only one set of rules applies to traffic entering and leaving the subnet, thereby maintaining clarity and predictability in network traffic management. This design helps in avoiding conflicts that could arise from having multiple ACLs operating on the same subnet, ensuring seamless network security and control.