Problems

Labs open a real Linux machine in your browser. Quizzes check the theory in a minute.

33 of 344 problems

Title	Topic	Acceptance	Difficulty	XP
Create a User AccountAdd an account with a specific shell, home directory, primary group, secondary groups and a locked password.easyLinux10 XP	Linux	New	easy	10
Add Groups Without Losing Old OnesGive a user two more supplementary groups while keeping the ones they already have.easyLinux10 XP	Linux	New	easy	10
Clear a Zombie Process LeakZombies are piling up. Find the parent that never reaps its children and deal with it.hardLinux40 XP	Linux	New	hard	40
firewalld Runtime vs PermanentYou run firewall-cmd --permanent --zone=public --add-service=https. The command prints success, but clients still cannot reach port 443. Nginx is listening. WhaeasyLinux3 XP	Linux	New	easy	3
autofs Indirect MapsYou configured autofs for NFS. /etc/auto.master.d/shares.autofs contains /shares /etc/auto.shares, and /etc/auto.shares contains data -rw,sync nfs1:/export/datahardLinux8 XP	Linux	New	hard	8
Rename Many Files SafelyBulk-rename file extensions with a loop that survives spaces and leaves everything else alone.easyShell10 XP	Shell	New	easy	10
Search and Replace Across Many FilesUpgrade every http:// endpoint to https:// in all config files of a tree, and only in config files.easyShell10 XP	Shell	New	easy	10
Top Talkers in an Access LogBuild a pipeline that finds the busiest client IPs in a web server log and formats the report exactly.mediumShell20 XP	Shell	New	medium	20
Fix a Script That Breaks on SpacesRepair word-splitting and globbing bugs so the script handles any file name.easyShell10 XP	Shell	New	easy	10
Keep Only the Newest BackupsWrite a pruning script that keeps the N most recent dated backups and deletes the rest.easyShell10 XP	Shell	New	easy	10
Wait for a Dependency with a TimeoutWrite a wait-for script that polls until a readiness file appears, or gives up on time.easyShell10 XP	Shell	New	easy	10
Publish a Repo to a RemoteAdd a remote, push main with upstream tracking, and publish a release tag.easyGit10 XP	Git	New	easy	10
CMD vs ENTRYPOINTAn image has ENTRYPOINT ["curl"] and CMD ["--help"]. What runs when you execute docker run myimage https://example.com?mediumDocker5 XP	Docker	New	medium	5
Inject a ConfigMap and a Secret as Env VarsCreate a ConfigMap and a Secret, then wire them into a Deployment's containers as environment variables.easyKubernetes10 XP	Kubernetes	New	easy	10
Add Readiness and Liveness ProbesGive a Deployment the health checks it is missing, so Kubernetes stops sending traffic to Pods that are not ready and restarts hung ones.mediumKubernetes20 XP	Kubernetes	New	medium	20
Add a Quota Without Breaking WorkloadsCap a namespace with a ResourceQuota and give it LimitRange defaults so a Deployment without resources keeps running.mediumKubernetes20 XP	Kubernetes	New	medium	20
A Role for Rolling Out AppsLet a CI ServiceAccount create and update workloads in one namespace, but never delete them or read Secrets.mediumKubernetes20 XP	Kubernetes	New	medium	20
Serve an App over HTTPS with IngressStore the provided certificate as a TLS Secret and publish the app over HTTPS on its host name with an Ingress.mediumKubernetes20 XP	Kubernetes	New	medium	20
A Service for a Database Outside the ClusterApps reach a legacy database through a Service with no selector, and connections hang. Fix its hand-made EndpointSlice so the Service points at the database.mediumKubernetes20 XP	Kubernetes	New	medium	20
Secrets as Files, Not Environment VariablesAn app reads its database password from an environment variable, where it leaks into crash dumps and debug output. Move it to a read-only file only the app's user can read.easyKubernetes10 XP	Kubernetes	New	easy	10
Restoring an etcd SnapshotOn a kubeadm cluster you took a backup with etcdctl snapshot save /opt/snap.db. After an accidental deletion you run etcdutl snapshot restore /opt/snap.db --dathardKubernetes8 XP	Kubernetes	New	hard	8
ConfigMaps vs SecretsWhat is true about a Kubernetes Secret by default?easyKubernetes3 XP	Kubernetes	New	easy	3
Liveness vs ReadinessA Pod's readiness probe starts failing while its liveness probe keeps succeeding. What happens?mediumKubernetes5 XP	Kubernetes	New	medium	5
ConfigMap Updates and subPathA container mounts key config.yaml from ConfigMap app-cfg with mountPath: /etc/app/config.yaml and subPath: config.yaml. You edit the ConfigMap. Ten minutes lathardKubernetes8 XP	Kubernetes	New	hard	8
What Makes It GitOpsWhich setup best matches the GitOps model?easyKubernetes3 XP	Kubernetes	New	easy	3
How Helm Treats CRDsA chart ships its CustomResourceDefinitions in the crds/ folder. Which statement about them is true?hardKubernetes8 XP	Kubernetes	New	hard	8
Security Groups Are StatefulA security group allows inbound TCP 443 from anywhere and has no outbound rules that match the client. Will responses to HTTPS requests reach the clients?mediumCloud5 XP	Cloud	New	medium	5
Auto Scaling SignalsYour web tier is CPU-bound and traffic doubles every evening. Which approach keeps latency stable at the lowest cost?mediumCloud5 XP	Cloud	New	medium	5
Organizations and SCPsA member account sits in an OU with a service control policy that denies all actions outside eu-central-1 and eu-west-1. An IAM user in that account has the AdmhardCloud8 XP	Cloud	New	hard	8
Carve Subnets Out of an Address BlockSplit a /22 into the smallest subnets that fit each team, without overlaps.mediumNetworking20 XP	Networking	New	medium	20
Overlapping NetworksWhich pair of networks overlaps?mediumNetworking5 XP	Networking	New	medium	5
What TLS Certificates ProveWhen your browser validates a server's TLS certificate, what is it mainly verifying?mediumNetworking5 XP	Networking	New	medium	5
One Resource per Item with for_eachGenerate a file for every service in a map, and add or remove services by editing the map only.mediumTerraform20 XP	Terraform	New	medium	20