How do DNS, load balancers, IAM and secrets fit together?

Definition:

DNS resolves names to records, load balancers select healthy destinations, IAM controls identities and permissions, and secret managers store sensitive credentials. These components connect an application to users and dependencies without putting all configuration into code. A failure at any layer can look like “the API is down” from the outside.

Key points:

• DNS maps names to records; a load balancer routes traffic to healthy instances.

• IAM controls who may access resources; service identities should have minimal access.

• A secret manager stores sensitive credentials; apps retrieve only what they need.

• Trace name resolution, connectivity, authentication and application response as separate stages during troubleshooting.

Interview point:

• Network access and permission are different: a reachable database may deny credentials, while valid credentials do not fix a blocked route.