DNS
The system that translates names (like example.com) into network addresses (like IPs), enabling service discovery and routing.
Definition
DNS (Domain Name System) translates human-friendly names into network addresses.
If an app connects to db.internal or api.example.com, DNS is the step that answers: “what IP address should I connect to right now?”
Why DNS matters
- Service discovery: names can point to different instances over time.
- Caching: results are cached, so changes may not take effect instantly.
- Failure modes: a DNS outage can look like “the network is down” even when the destination is healthy.
DNS is often the first hop in “my app can’t connect to that service”.