DNS records are the address book of the internet, and the Professional Cloud Architect exam expects you to know the basics of how they work alongside Cloud DNS and load balancing on Google Cloud. This is a small topic, but a few questions on the exam touch it directly, and many more rely on it as background knowledge for traffic routing scenarios.
A DNS record is an entry in the Domain Name System that tells the internet how to translate a human-readable domain name into something a machine can route to. When someone types example.com into a browser, their resolver walks the DNS hierarchy, eventually lands on the authoritative DNS provider for that domain, and reads the records there to figure out where to send the request.
On Google Cloud, the authoritative DNS provider is usually Cloud DNS, although you can use any provider you want and still point traffic at GCP resources.
For the Professional Cloud Architect exam, three record types matter.
A records map a domain name to an IPv4 address. So example.com might resolve to 192.0.2.1. This is the most common record type and the one you will see most often in architecture diagrams.
AAAA records (sometimes written as AAA in shorthand) map a domain name to an IPv6 address. So example.com might resolve to 2001:db8::1. As IPv6 adoption grows, AAAA records matter more, especially for clients on networks that prefer IPv6.
CNAME records map a domain name to another domain name. So www.example.com might be a CNAME pointing to example.com. This is useful when you want multiple names to resolve to the same service without duplicating the underlying IP information in multiple places.
The path of a user request usually looks like this. The user types your domain into a browser. Their resolver asks Cloud DNS for the IP address. Cloud DNS returns the IP of your load balancer. The browser sends the request to that IP, and Cloud Load Balancing distributes the request to a healthy backend.
So the DNS record is the first hop. It does not do any intelligent routing on its own. It just hands the client an IP, and from there the load balancer takes over with health checks, routing rules, and backend selection.
This matters for the exam because PCA scenarios often describe a user accessing a global application, and you need to recognize that DNS is what gets them to the load balancer in the first place. If a question asks how to direct traffic from a custom domain to a global HTTP load balancer, the answer involves an A or AAAA record pointing at the load balancer's IP, not a CNAME.
You generally cannot use a CNAME at the apex of a domain. So example.com itself usually needs an A or AAAA record, while www.example.com can be a CNAME. Cloud DNS supports this same convention, so the rule applies whether you are using Cloud DNS or another provider.
My Professional Cloud Architect course covers DNS records on GCP alongside the rest of the architecture and compliance material.
