DNS is one of those topics where the underlying ideas are simpler than the jargon makes them sound. This article covers the three DNS record types the Associate Cloud Engineer exam expects you to know, what each one does, where Cloud DNS fits in, and the basic flow of how a user's request reaches a GCP-hosted application.
It does not cover MX records, TXT records, SRV records, or the more exotic record types. Those exist and matter in real life, but the ACE exam is narrow here. A, AAAA, and CNAME are the three to know.
DNS stands for Domain Name System. A DNS record is an entry that maps a human-readable name like www.example.com to something a computer can use to reach the actual service. That something is usually an IP address, but it can also be another domain name.
You configure these records in a DNS provider. On GCP, the native option is Cloud DNS. You could also use a third-party provider like Cloudflare or Route 53. The records work the same way regardless of provider. Cloud DNS just gives you a Google-managed place to put them.
An A record maps a domain name to an IPv4 address. example.com points to 192.0.2.1. That is what an A record does. This is the original, fundamental DNS record type and it is by far the most common. When you set up a website or an API and you want a friendly domain name to point to a load balancer, you create an A record.
An AAAA record (sometimes written as "quad-A") does the same thing as an A record, but for IPv6 addresses. example.com points to 2001:db8::1. As more clients adopt IPv6, AAAA records matter more. For the Associate Cloud Engineer exam, the thing to know is the basic mapping: A is for IPv4, AAAA is for IPv6.
A CNAME record is an alias. It maps one domain name to another domain name, not to an IP address. For example, www.example.com is a CNAME pointing to example.com. When a client looks up www.example.com, the DNS resolver sees the CNAME, follows it to example.com, and then resolves example.com (which has its own A or AAAA record) to an IP.
The reason CNAMEs exist is so you can point multiple names at the same underlying service without having to update the IP address in multiple places. If example.com's IP changes, you only update the A record on example.com. The www.example.com CNAME just keeps pointing to example.com and automatically resolves to the new IP.
The flow looks like this. A user types your domain into a browser. The browser asks DNS for the IP. DNS (Cloud DNS, in this case) returns the IP from your A record, which is the IP of your Cloud Load Balancer. The browser opens a connection to the load balancer. The load balancer routes the request to one of your backend services - Compute Engine, GKE, App Engine, Cloud Run, whatever is behind it.
So DNS is the very first step in the path. It is what turns the domain name into an address the rest of the system can reach. Once the load balancer has the request, Cloud Load Balancing takes over and distributes traffic to backends based on health checks and routing rules.
The Associate Cloud Engineer exam keeps DNS questions narrow. The patterns I see most often are these.
If the question asks about mapping a domain name to a load balancer's IPv4 address, the answer is an A record. If the question asks about mapping a domain name to an IPv6 address, AAAA. If the question asks about pointing one name (like www.example.com) at another name (like example.com), CNAME.
If you see in the question terms like canonical name, alias for a domain, or pointing one hostname at another hostname, think CNAME. If you see specifically IPv6 addresses, think AAAA. The default is A.
The exam may also ask which Google Cloud service is the managed DNS provider. The answer is Cloud DNS. It is the GCP-native way to host DNS zones for your domains.
DNS is the lookup layer that turns names into addresses. A records handle IPv4. AAAA records handle IPv6. CNAME records alias one name to another. Cloud DNS is GCP's managed DNS provider, and it sits at the front of the request path before traffic ever reaches your load balancer.
For the Associate Cloud Engineer exam, you need to recognize the three record types and the basic flow of DNS to load balancer to backend. That is essentially the full scope of what gets tested here.
My Associate Cloud Engineer course covers DNS records and Cloud DNS in the networking section alongside the rest of the load balancing topics that show up on the ACE exam.
