The answer is that no telemetry subscription is configured on the router for the desired data paths. In gRPC telemetry, the router’s gRPC server simply listens for incoming connections and manages transport, but it does not automatically push data; a subscription must explicitly define which YANG data paths to stream and at what cadence. Without that subscription, the server has no instructions on what to send, so even though the server is running and the collector is reachable, no telemetry data flows. On the ENCOR 350-401 exam, this question tests your understanding that streaming telemetry requires a three-part chain: a functional server, network reachability, and a configured subscription—the subscription is the most commonly overlooked piece. A common trap is assuming a running server implies data is being sent, but the server is passive until a subscription activates it. Memory tip: think of the subscription as the “playlist” for the server—without it, the server is just an idle speaker with no songs queued.
350-401 NetFlow and Telemetry Practice Question
This 350-401 practice question tests your understanding of netflow and telemetry. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer is deploying streaming telemetry from a Cisco ASR 1000 router to a collector using gRPC. The engineer notices that the telemetry data is not being received by the collector. The router shows that the gRPC server is running and the collector is reachable. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No telemetry subscription is configured on the router for the desired data paths.
For gRPC telemetry, the router must have a subscription configured to send data. Option A is correct because without a subscription, no data is streamed. Option B is incorrect because the server is running. Option C is incorrect because the collector is reachable. Option D is incorrect because the encoding format does not prevent data from being sent if the server is up.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
No telemetry subscription is configured on the router for the desired data paths.
Why this is correct
Correct because a subscription defines what data to stream and to which collector; without it, no data is sent.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The gRPC server is configured with the wrong port number.
Why it's wrong here
Incorrect because the server is running, indicating the port is correctly configured.
✗
The collector is not listening on the same IP address as configured on the router.
Why it's wrong here
Incorrect because the collector is reachable, implying it is listening on the correct IP.
✗
The telemetry data is encoded in GPB, but the collector expects JSON.
Why it's wrong here
Incorrect because the encoding format mismatch would cause parsing errors, but data would still be sent; the issue is no data at all.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
NetFlow and Telemetry — This question tests NetFlow and Telemetry — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: No telemetry subscription is configured on the router for the desired data paths. — For gRPC telemetry, the router must have a subscription configured to send data. Option A is correct because without a subscription, no data is streamed. Option B is incorrect because the server is running. Option C is incorrect because the collector is reachable. Option D is incorrect because the encoding format does not prevent data from being sent if the server is up.
What should I do if I get this 350-401 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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