How cloud DNS resolves a URL to an IP

WHAT THIS TESTS The question checks that you grasp the layered, hierarchical nature of DNS and can place a managed cloud DNS service correctly as the authoritative source for your domain.

A GOOD ANSWER COVERS First the browser and operating system check their own caches. On a miss, the request goes to a recursive resolver, often run by the ISP or a public provider like 8.8.8.8. The resolver, if it has nothing cached, queries a root nameserver, which returns the address of the top level domain servers for the extension such as .com. The TLD server returns the authoritative nameservers for your domain, which are your cloud DNS zone, for example Route 53 or Azure DNS. The resolver queries that zone, which returns the A record for IPv4 or AAAA for IPv6. The resolver hands the IP back to the browser, which opens a TCP connection. Every step caches the answer for the duration of the record's TTL, so subsequent lookups are far faster and may never reach the authoritative tier.

COMMON WRONG ANSWERS Describing resolution as a single direct call to your server skips the resolver and root and TLD hierarchy. Forgetting caching and TTL misses why DNS scales and why propagation delays exist. Confusing authoritative and recursive roles is a frequent slip.

LIKELY FOLLOW-UPS What is the difference between an A record and a CNAME? How does a low TTL affect failover and load? What is an alias record in Route 53?

ONE CONCRETE EXAMPLE A user opens app.example.com. The resolver learns from .com servers that Route 53 is authoritative, queries the hosted zone, and gets an alias record pointing at a load balancer's IP, all cached for sixty seconds so a regional failover takes effect quickly.