CKAD Probe handler Practice Question
Which FOUR of the following are valid probe handlers in Kubernetes?
⚠ Common exam trap
Candidates may mistakenly think only the original three (exec, httpGet, tcpSocket) are valid, overlooking gRPC which has been supported since v1.24. Conversely, they might include udpSocket because it is a common network protocol.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
exec
In Kubernetes, the kubelet supports exactly four probe handler mechanisms for liveness, readiness, and startup probes. Option A (exec) is correct because it runs a command inside the container and uses the exit code to determine success. Option B (gRPC) is correct because Kubernetes supports gRPC health checking (GA since v1.24) via the gRPC Health Checking Protocol. Option C (httpGet) is correct because it performs an HTTP GET request against the container's IP and port, treating 200-399 status codes as success. Option D (tcpSocket) is correct because it attempts a TCP connection to the specified port, succeeding if the connection is established. Option E (udpSocket) is not a valid handler, as Kubernetes does not provide a UDP-based probe type; probes use exec, httpGet, tcpSocket, or gRPC only.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
exec
Why this is correct
The `exec` handler runs a command inside the container, treating exit code 0 as success. It satisfies the stem's requirement for a valid probe handler, alongside `httpGet`, `tcpSocket` and `grpc`. This mechanism suits liveness and readiness checks needing custom logic unavailable through network or command probes alone.
- ✓
gRPC
Why this is correct
gRPC is a valid probe handler, introduced as beta in Kubernetes 1.24. It performs a remote procedure call against the container's gRPC health-checking protocol, satisfying the stem's requirement for a legitimate handler alongside httpGet, tcpSocket and exec.
- ✓
httpGet
Why this is correct
httpGet is a valid Kubernetes probe handler, issuing an HTTP GET request against the container's IP on a specified path and port. A 200-399 response marks the probe successful, satisfying the stem's requirement for valid probe handlers.
- ✓
tcpSocket
Why this is correct
tcpSocket is a valid Kubernetes probe handler, opening a TCP connection to the container's specified port. A successful connection marks the probe successful, satisfying the stem's requirement for valid probe handlers alongside exec, httpGet and grpc.
- ✗
udpSocket
Why it's wrong here
Kubernetes defines exactly three probe handlers: exec, httpGet and tcpSocket. There is no udpSocket handler, since UDP is connectionless and cannot confirm application liveness through a handshake. A UDP service would need an exec command or a TCP health endpoint instead.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKAD practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKAD exam.