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CNCF CKA Practice Test 60

Question 590

At Northstar finance, in an isolated training cluster during a scheduled maintenance rehearsal: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which Kubernetes behavior best explains the required change or diagnosis?

  1. CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.
  2. Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution.
  3. DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist.
  4. NetworkPolicy egress rules are additive and DNS lookup requires permitted traffic to the DNS server, not only a correct Service record.

Explanation

Correct Answer

A:

CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. This explains the stated condition. The corresponding action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The direct acceptance evidence is: Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger.

Incorrect Answers

B:

Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution. That explanation applies to a different technical failure. Here the controlling principle is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

C:

The offered statement is true for this other mechanism: DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist. It does not explain the facts described here, which follow from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

D:

This principle describes a separate cause: NetworkPolicy egress rules are additive and DNS lookup requires permitted traffic to the DNS server, not only a correct Service record. The reported condition is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The two mechanisms should not be conflated.

Question 591

At Northstar finance, in an isolated training cluster during a scheduled maintenance rehearsal: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which observation best verifies the requested outcome rather than an unrelated state?

  1. Compare listed endpoints against the matching ready Pods and expected selector for invoice-svc.
  2. Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger.
  3. Run kubectl -n kube-system logs deployment/coredns --tail=50 and compare to an in-Pod resolution test.
  4. Compare the Corefile's Kubernetes plugin zone with expected cluster.local and sample Pod resolv.conf data.

Explanation

Correct Answer

B:

Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger. This validates the affected object or control path, rather than only showing a command completed. The underlying reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The intended action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change.

Incorrect Answers

A:

The alternative verifies a different condition: EndpointSlices represent Service backend addresses and readiness; Service existence alone does not prove endpoints exist. The current case instead depends on: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Confirm that “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger”.

C:

This observation would test a different technical dependency: DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist. The current issue is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its decisive check is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger”.

D:

The alternative verifies a different condition: CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide. The current case instead depends on: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Confirm that “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from ledger”.

Question 592

At Northstar finance, in an isolated training cluster during a scheduled maintenance rehearsal: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which operational control most directly prevents this failure or configuration drift?

  1. Audit controller capability and exposed service access policies before enabling public ingress.
  2. Test security policies from allowed and denied sources rather than trusting YAML alone.
  3. Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS.
  4. Manage Service selectors and target ports alongside the Deployment labels and container listening port.

Explanation

Correct Answer

C:

Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS. This reduces recurrence of the specific operational failure. It reinforces the action: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The relevant mechanism is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

Incorrect Answers

A:

That safeguard is relevant to: LoadBalancer Services request external routing from a supported infrastructure controller; a bare cluster does not guarantee an external address. The current failure instead follows from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its prevention measure is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

B:

This routine guards against another mechanism: A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress. The recurring exposure in the current case is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The matching preventive check is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

D:

That safeguard is relevant to: A ClusterIP Service provides stable in-cluster virtual addressing and directs traffic to selected ready Pod endpoints. The current failure instead follows from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its prevention measure is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

Question 593

At Horizon observability, in a disposable simulated environment during a monitored release window: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which command or initial safe diagnostic step best addresses the stated lab task?

  1. Run kubectl -n kube-system rollout restart deployment/coredns after the approved change.
  2. Run kubectl -n observability apply -f ./policies/metrics-api-dns.yaml where egress grants UDP and TCP 53 to validated DNS destinations.
  3. Run kubectl -n observability patch service metrics-svc --type=merge -p '{"spec":{"ports":[{"port":8080,"targetPort":3000}]}}' for the lab's single-port Service.
  4. Run kubectl -n kube-system get configmap coredns -o yaml and review the Corefile.

Explanation

Correct Answer

A:

Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. This is the appropriate command-line action or first safe diagnostic. The technical reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Validate the result with: Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability. Execute changes only in an authorized disposable lab or after normal production change controls.

Incorrect Answers

B:

The proposed action belongs to the mechanism: NetworkPolicy egress rules are additive and DNS lookup requires permitted traffic to the DNS server, not only a correct Service record. Here the stated fault follows a different mechanism: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The corrective choice is “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change”.

C:

The offered action targets: The Service port is what clients connect to, while targetPort must reach the actual backend listener. The case facts point instead to: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Implement “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change” to address that specific condition.

D:

This alternative is a response to another technical cause: CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide. The reported case instead depends on: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The action that directly addresses it is “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change”.

Question 594

At Horizon observability, in a disposable simulated environment during a monitored release window: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which Kubernetes behavior best explains the required change or diagnosis?

  1. Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution.
  2. CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.
  3. A ClusterIP Service provides stable in-cluster virtual addressing and directs traffic to selected ready Pod endpoints.
  4. The Service port is what clients connect to, while targetPort must reach the actual backend listener.

Explanation

Correct Answer

B:

CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. This explains the stated condition. The corresponding action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The direct acceptance evidence is: Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability.

Incorrect Answers

A:

Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution. That explanation applies to a different technical failure. Here the controlling principle is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

C:

This principle describes a separate cause: A ClusterIP Service provides stable in-cluster virtual addressing and directs traffic to selected ready Pod endpoints. The reported condition is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The two mechanisms should not be conflated.

D:

The Service port is what clients connect to, while targetPort must reach the actual backend listener. That explanation applies to a different technical failure. Here the controlling principle is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

Question 595

At Horizon observability, in a disposable simulated environment during a monitored release window: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which observation best verifies the requested outcome rather than an unrelated state?

  1. Run authorized connectivity probes from both approved and unapproved namespaces.
  2. Compare the Corefile's Kubernetes plugin zone with expected cluster.local and sample Pod resolv.conf data.
  3. Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability.
  4. Run an in-Pod nslookup metrics-svc.observability.svc.cluster.local and confirm name resolution under isolation.

Explanation

Correct Answer

C:

Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability. This validates the affected object or control path, rather than only showing a command completed. The underlying reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The intended action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change.

Incorrect Answers

A:

That test belongs to another control with this basis: A namespaceSelector in a NetworkPolicy ingress peer matches namespace labels; it differs from matching arbitrary Pod labels across namespaces. In the current case, the governing reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The direct verification is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability”.

B:

This observation would test a different technical dependency: CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide. The current issue is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its decisive check is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability”.

D:

That test belongs to another control with this basis: NetworkPolicy egress rules are additive and DNS lookup requires permitted traffic to the DNS server, not only a correct Service record. In the current case, the governing reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The direct verification is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from observability”.

Question 596

At Horizon observability, in a disposable simulated environment during a monitored release window: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which operational control most directly prevents this failure or configuration drift?

  1. Test security policies from allowed and denied sources rather than trusting YAML alone.
  2. Monitor DNS replica readiness, restart trends and upstream resolution errors.
  3. Maintain lightweight in-cluster DNS canaries and verify Service creation and DNS freshness.
  4. Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS.

Explanation

Correct Answer

D:

Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS. This reduces recurrence of the specific operational failure. It reinforces the action: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The relevant mechanism is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Applied here, the relevant facts are: needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. The question asks which operational control most directly prevents this failure or configuration drift.

Incorrect Answers

A:

This routine guards against another mechanism: A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress. The recurring exposure in the current case is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The matching preventive check is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

B:

The suggested review tracks a different technical risk: DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist. Here the sustained control must address: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Choose “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

C:

That safeguard is relevant to: Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution. The current failure instead follows from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its prevention measure is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

Question 597

At Pinecrest logistics, in a sandbox Kubernetes cluster during a recovery tabletop exercise: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which command or initial safe diagnostic step best addresses the stated lab task?

  1. Run kubectl -n fulfillment apply -f ./policies/dispatch-api-deny-ingress.yaml after validating selectors and the CNI's policy enforcement support.
  2. Run kubectl -n kube-system rollout restart deployment/coredns after the approved change.
  3. Run kubectl -n fulfillment apply -f ./policies/dispatch-api-peer.yaml after verifying podSelector rules match the source identity.
  4. Run kubectl -n kube-system get deploy coredns; kubectl -n kube-system get pods -l k8s-app=kube-dns.

Explanation

Correct Answer

B:

Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. This is the appropriate command-line action or first safe diagnostic. The technical reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Validate the result with: Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment. Execute changes only in an authorized disposable lab or after normal production change controls.

Incorrect Answers

A:

The proposed action belongs to the mechanism: A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress. Here the stated fault follows a different mechanism: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The corrective choice is “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change”.

C:

This alternative is a response to another technical cause: An ingress rule with a podSelector selects source Pods in its own namespace unless combined with other peer selectors. The reported case instead depends on: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The action that directly addresses it is “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change”.

D:

The proposed action belongs to the mechanism: DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist. Here the stated fault follows a different mechanism: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The corrective choice is “Run kubectl -n kube-system rollout restart deployment/coredns after the approved change”.

Question 598

At Pinecrest logistics, in a sandbox Kubernetes cluster during a recovery tabletop exercise: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which Kubernetes behavior best explains the required change or diagnosis?

  1. CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide.
  2. A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress.
  3. CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.
  4. A namespaceSelector in a NetworkPolicy ingress peer matches namespace labels; it differs from matching arbitrary Pod labels across namespaces.

Explanation

Correct Answer

C:

CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. This explains the stated condition. The corresponding action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The direct acceptance evidence is: Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment.

Incorrect Answers

A:

The offered statement is true for this other mechanism: CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide. It does not explain the facts described here, which follow from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

B:

This principle describes a separate cause: A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress. The reported condition is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The two mechanisms should not be conflated.

D:

The offered statement is true for this other mechanism: A namespaceSelector in a NetworkPolicy ingress peer matches namespace labels; it differs from matching arbitrary Pod labels across namespaces. It does not explain the facts described here, which follow from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy.

Question 599

At Pinecrest logistics, in a sandbox Kubernetes cluster during a recovery tabletop exercise: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which observation best verifies the requested outcome rather than an unrelated state?

  1. Compare the Corefile's Kubernetes plugin zone with expected cluster.local and sample Pod resolv.conf data.
  2. Run kubectl -n kube-system logs deployment/coredns --tail=50 and compare to an in-Pod resolution test.
  3. Run curl -fsS http://127.0.0.1:18082/healthz from another local shell while the tunnel is active.
  4. Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment.

Explanation

Correct Answer

D:

Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment. This validates the affected object or control path, rather than only showing a command completed. The underlying reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The intended action is: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change.

Incorrect Answers

A:

This observation would test a different technical dependency: CoreDNS behavior is configured separately from Service definitions, and incorrect DNS plugins or cluster domain can break discovery cluster-wide. The current issue is governed by: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its decisive check is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment”.

B:

The alternative verifies a different condition: DNS resolution may fail when CoreDNS replicas are unhealthy even when the requested Service and Pod endpoints exist. The current case instead depends on: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Confirm that “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment”.

C:

That test belongs to another control with this basis: Port-forwarding creates a client-side tunnel to a selected backend and does not change the Service type or network exposure. In the current case, the governing reason is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The direct verification is “Run kubectl -n kube-system rollout status deployment/coredns then test a Service lookup from fulfillment”.

Question 600

At Pinecrest logistics, in a sandbox Kubernetes cluster during a recovery tabletop exercise: A reviewed CoreDNS ConfigMap change needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. Which operational control most directly prevents this failure or configuration drift?

  1. Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS.
  2. Manage Service selectors and target ports alongside the Deployment labels and container listening port.
  3. Maintain lightweight in-cluster DNS canaries and verify Service creation and DNS freshness.
  4. Test security policies from allowed and denied sources rather than trusting YAML alone.

Explanation

Correct Answer

A:

Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS. This reduces recurrence of the specific operational failure. It reinforces the action: Run kubectl -n kube-system rollout restart deployment/coredns after the approved change. The relevant mechanism is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Applied here, the relevant facts are: needs a controlled DNS Deployment restart in kube-system; a healthy rollout is required. Work only within the stated target and verify before declaring success. The question asks which operational control most directly prevents this failure or configuration drift. The choice being evaluated here is: Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS. The case setting is: At Pinecrest logistics, in a sandbox Kubernetes cluster during a recovery tabletop exercise: A reviewed CoreDNS ConfigMap change n.

Incorrect Answers

B:

That safeguard is relevant to: A ClusterIP Service provides stable in-cluster virtual addressing and directs traffic to selected ready Pod endpoints. The current failure instead follows from: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Its prevention measure is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

C:

This routine guards against another mechanism: Cluster DNS should resolve Service names inside its configured domain; host-side DNS results do not prove in-cluster resolution. The recurring exposure in the current case is: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. The matching preventive check is “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.

D:

The suggested review tracks a different technical risk: A selecting NetworkPolicy with ingress isolation and no allow rules denies new ingress to selected Pods except protocol-specific policy behavior; it does not itself control egress. Here the sustained control must address: CoreDNS Pods need a restart when configuration update behavior requires it; a Deployment restart replaces Pods under its rollout strategy. Choose “Stage CoreDNS changes and preserve rollback capability before restarting cluster-wide DNS”.