← Problem Library
K8s L4 K8S 114 · 15 min

NetworkPolicy allows the namespace selector but cluster DNS still fails because the egress rule forgot UDP 53

The app can reach peer services, yet name resolution breaks because the policy only modeled TCP while the resolver path still needs UDP.

K8sFoundation OpsLevel 4Free15 min
Scenario

The app can reach peer services, yet name resolution breaks because the policy only modeled TCP while the resolver path still needs UDP.

What to check first
  • Identify the primary failure signal in the Half-open DNS Egress scenario.
  • Separate visible symptoms from the underlying technical dependency.
  • Describe the safest recovery path and the follow-up prevention work.
Checking checklist
  1. Summarize the current impact and the last known change.
  2. Collect direct evidence from logs, runtime state, and configuration before changing anything.
  3. Separate immediate recovery from permanent prevention work.
Recovery and prevention

Choose the smallest safe recovery action first, then record the prevention work that reduces repeat incidents.

Questions worth viewing together
Should I translate commands, logs, or product names?

No. Keep commands, logs, file names, APIs, and product names unchanged, then explain the reasoning in the selected UI language.

What should the answer focus on?

State the root cause, the evidence that supports it, and the safest recovery direction.

Why can the scenario remain in the original language?

The source scenario is treated as an incident artifact. Guidance, checklist, hints, and explanations can be localized around it.