Cloud NAT is a managed service that lets virtual machines and other resources without external IP addresses make outbound connections to the internet. NAT stands for Network Address Translation, a technique that maps private IP addresses to public ones so that resources on a private network can communicate with external networks. On Google Cloud, Cloud NAT applies that mapping at the VPC level, which means resources can stay private while still reaching external APIs and services. For the Professional Cloud Database Engineer exam, the point to hold onto is that Cloud NAT covers outbound traffic only, and it is the standard way to give private resources internet access without assigning each one a public IP.
Consider a VPC network with a subnet that holds a few VM instances, each carrying an internal IP only and no external IP. By default those instances cannot reach the internet directly, because they have no public address to send from or receive on. To change that, you configure Cloud NAT as a managed NAT gateway for the VPC network. It handles outbound traffic for the resources in your subnets from a central place, so you do not configure anything on the individual instances.
When one of those instances initiates an outbound request, Cloud NAT translates its internal IP to a public IP assigned to the NAT gateway, and the request goes out to the internet using that public address. When the response comes back, the public IP receives it and Cloud NAT maps it back to the internal IP of the instance that made the request. Cloud NAT maintains this mapping for the duration of the session, so each response reaches the correct instance with no additional configuration. The instance receives the data as if it had communicated with the internet directly, while its private IP stays shielded from direct exposure.
Database resources are usually the kind of workload you want to keep off the public internet. They hold sensitive data, and exposing them with external IPs widens the surface that an attacker can reach. At the same time, those resources sometimes need outbound connectivity, for tasks such as pulling updates or calling an external service. Cloud NAT resolves that tension by allowing the outbound path while keeping the resources private, which is why it comes up in the context of designing secure database environments on Google Cloud.
A few properties of Cloud NAT are worth knowing for the Professional Cloud Database Engineer exam. The first is security. Because resources do not need external IPs to reach the internet, the attack surface is smaller, and Cloud NAT does not allow unsolicited inbound connections, which removes a common entry point for attackers.
The second is scaling. Cloud NAT adjusts automatically as the number of resources grows or network traffic increases, so performance stays consistent without manual intervention. The third is availability. Cloud NAT is designed with no single point of failure, which lets it provide reliable connectivity with minimal risk of downtime.
The fourth is cost. External IP addresses cost money, and assigning one to every resource adds up. Because Cloud NAT provides shared outbound access, you do not need to allocate a public IP to each instance, which can lead to meaningful savings as the environment grows.
Put together, these points describe what Cloud NAT is for. It gives private resources a managed, scalable, and cost-effective path to the internet for outbound connections, without external IPs and without opening those resources to inbound traffic from outside.
Our Professional Cloud Database Engineer course covers Cloud NAT alongside VPC networking and private database connectivity, with practice questions that drill these distinctions.
