Certification955 problems· 24 reviewed

CKA

955 incident response problems that help with CKA prep.

All problems (955)

K8S-024Pod restartsThe file exists and the volume is mounted, but the runtime user cannot read the config because the mode is too strict.KubernetesBeginner15 minFreeK8S-077CoreDNS negative caching masks a fixed service record long after the backend issue is goneThe service entry is corrected, but clients still fail because the resolver path is serving a negative cache response longer than operators expect.KubernetesIntermediate16 minFreeK8S-120Node feature label disappears during upgrade and the GPU DaemonSet silently unschedules from every new workerThe nodes join successfully, yet the supporting workload never follows because the upgrade process changed or dropped the advertised feature label.KubernetesIntermediate16 minFreeK8S-113PersistentVolume expansion finishes in the controller but the filesystem resize never happensCapacity looks larger in the API, yet the container still sees the old filesystem size because the final online resize step never occurred.KubernetesIntermediate16 minFreeK8S-108Service internalTrafficPolicy Local blackholes requests after a scale down leaves one node without local endpointsThe service stays healthy overall, but clients on one node get failures because the policy forbids cross-node forwarding after endpoint placement changes.KubernetesIntermediate16 minFreeK8S-078NodeLocal DNSCache keeps using the old upstream after a ConfigMap updateCluster DNS works partially, but one set of nodes still forwards to the retired resolver because the node-local cache path never reloaded the new upstream config.KubernetesIntermediate17 minFreeK8S-122Pod anti-affinity is only preferred, so after a zone loss the replacement replicas pile onto one node and the next failure takes out the whole serviceAvailability degrades quietly because the scheduler still honors availability under pressure, just not in the way the team assumed.KubernetesIntermediate17 minFreeK8S-093Service selector is correct but EndpointSlice labels point the controller at the wrong shardThe Service definition looks fine, yet traffic still misses the intended backend because a generated EndpointSlice path is bound to an outdated label set.KubernetesIntermediate17 minFreeK8S-067StatefulSet ordinal DNS looks healthy but traffic is emptyPod names resolve as expected, yet clients get no working backend because the Service that should back ordinal DNS no longer selects the current pods.KubernetesIntermediate17 minFreeK8S-057CoreDNS stub domain forwards the internal zone to the wrong upstreamMost cluster DNS works, but one internal zone fails because the custom forwarding block points at an outdated resolver target.KubernetesIntermediate18 minFreeK8S-064NetworkPolicy allows UDP 53 but blocks DNS TCP fallback for large responsesMost lookups appear healthy, yet one domain consistently fails because the policy only permits the UDP path and the resolver falls back to TCP for bigger answers.KubernetesIntermediate18 minFreeK8S-006A ConfigMap key name difference makes the config file look emptyA situation where the mount succeeds but the file name the application expects differs, so it does not work.KubernetesIntermediate19 minFreeK8S-063Mutating webhook injects a sidecar and the startupProbe now points at the wrong portThe pod definition still looks valid, but startup keeps failing because the injected sidecar changed the effective port assumptions of the main container.KubernetesIntermediate19 minFreeK8S-058Projected Secret rotates but the app never sees the new value through subPathSecret rotation works at the volume level, yet the application keeps using the old value because the file is mounted through a subPath that does not refresh.KubernetesIntermediate19 minFreeK8S-1617A Deployment rollout hangsA rollout hangs after moving the app port behind a sidecar.KubernetesBeginner8 minFreeK8S-1707A HorizontalPodAutoscaler sees metrics and one target still reads zeroAn HPA still reads zero after metric exposure was fixed.KubernetesBeginner8 minFreeK8S-1786A readiness path is corrected and one pod still stays unreadyA pod still stays unready after the readiness fix.KubernetesBeginner8 minFreeK8S-1796A readiness path is fixed and one pod still stays unreadyA pod still stays unready after the readiness fix.KubernetesBeginner8 minFreeK8S-1806A readiness path is fixed and one pod still stays unreadyA pod still stays unready after the readiness fix.KubernetesBeginner8 minFreeK8S-1726A readiness probe is correct and one pod still stays unreadyA pod still stays unready after a readiness probe fix.KubernetesBeginner8 minFree