Troubleshooting·Certified Kubernetes Application Developer
A Service With Endpoints and No Traffic
The Service failure that passes every check people run first. This walks the three port numbers that have to agree, asks the container which one it actually serves, and fixes it with a single field.
Services and Networking Guide 39 of 44 Intermediate
- Kubernetes1.36.4
- Runtimecontainerd 2.2.6
- CNICalico v3.32.1
- TimeAbout 15 min
- Reviewed26 August 2026
Written against the versions above. curl's exit codes are the diagnosis here: 7 is a failure to connect, 28 is a timeout, and they mean different things.
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| CKA1001 | 192.168.0.175 | Ubuntu 26.04 LTS | Control Plane Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE01 | 192.168.0.176 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE02 | 192.168.0.177 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
| CKA1001-NODE03 | 192.168.0.178 | Ubuntu 26.04 LTS | Worker Node | 2 Core | 4 GB | 50 GB |
Before you start
- guide 66 - the failure where there are no endpoints at all, which this one is deliberately not.
-
A Service that looks entirely healthy
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Prove the symptom from a client
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Read the three numbers that have to agree
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Ask the container what it is actually listening on
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Fix the one field and prove it