NAT Gateway is a network cloud service that supports IP address translation, and can provide Network Address Translation for computing instances in a VPC (Virtual Private Cloud). It is divided into two functions of SNAT and DNAT. Through SNAT, multiple ECSs can share EIP to access the Internet. Through DNAT, multiple ECSs can provide Internet services. The NAT Gateway is the ingress and egress of the Internet traffic in the VPC, which protects the private network information from being directly exposed on the Internet.