Service discovery via DNS in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is service discovery in Kubernetes?

Service discovery is the process that allows applications to find and communicate with each other automatically within a Kubernetes cluster.

beginner

How does Kubernetes use DNS for service discovery?

Kubernetes automatically creates DNS entries for services, so pods can find services by their DNS names instead of IP addresses.

intermediate

What is the DNS name format for a Kubernetes service?

The DNS name format is .<namespace>.svc.cluster.local, where is the service's name and <namespace> is its namespace.

intermediate

What role does CoreDNS play in Kubernetes service discovery?

CoreDNS is the DNS server inside Kubernetes that answers DNS queries for services and pods, enabling service discovery via DNS.

beginner

Why is DNS-based service discovery preferred over hardcoding IP addresses?

Because IP addresses can change when pods restart or move, DNS names provide a stable way to find services without manual updates.

What is the default DNS suffix for services in Kubernetes?

A service.local

B cluster.svc.local

C kube.local

D svc.cluster.local

The default DNS suffix for Kubernetes services is svc.cluster.local.

Which Kubernetes component handles DNS queries for service discovery?

A kube-scheduler

B CoreDNS

C etcd

D kube-proxy

CoreDNS is the DNS server that handles service discovery DNS queries in Kubernetes.

How can a pod find a service named 'web' in the 'default' namespace?

A web.svc.default.cluster.local

B default.web.svc.cluster.local

C web.default.svc.cluster.local

D svc.web.default.cluster.local

The correct DNS name format is ..svc.cluster.local, so 'web.default.svc.cluster.local' is correct.

Why should you avoid hardcoding service IP addresses in your application?

A IP addresses can change when pods restart or move

B IP addresses are always static in Kubernetes

C DNS is slower than IP addresses

D Hardcoding IPs improves scalability

Pods and services can get new IPs, so hardcoding IPs can break communication.

What happens if CoreDNS is not running in a Kubernetes cluster?

A Service discovery via DNS will fail

B Pods will still resolve services by IP

C Services will be discovered faster

D Nothing changes

Without CoreDNS, DNS queries for services fail, breaking service discovery.

Explain how DNS-based service discovery works in Kubernetes.

Think about how pods find each other without knowing IP addresses.

Why is using DNS for service discovery better than using fixed IP addresses in Kubernetes?

Consider what happens when pods restart or move.