350-501 Automation and Assurance Practice Question
Exhibit
Router# show telemetry ietf subscription 101 Subscription ID: 101 State: Invalid Stream: yang-push Encoding: encode-kvgpb Filter: xpath: /interfaces-interface-state Update policy: periodic: 500 Receivers: Address: 192.168.1.1 Port: 57500 Protocol: grpc TLS: false Errors: Last error: Connection refused to receiver 192.168.1.1:57500
Refer to the exhibit. An engineer configured a telemetry subscription to push interface state data to a collector. The subscription shows 'State: Invalid'. What is the most likely cause?
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
✓
The collector at 192.168.1.1:57500 is not reachable or the service is down.
The 'State: Invalid' with an associated error such as 'Connection refused' indicates that the subscription cannot reach the collector. This is typically due to the collector not being reachable or the service not listening on the specified port. Therefore, option B is correct. Option A is incorrect because 'encode-kvgpb' is a valid encoding for gRPC telemetry. Option C is incorrect because the xpath '/interfaces/interface/state' is correctly formatted. Option D is incorrect because a periodic update interval of 500 ms is acceptable and not the cause of the invalid state.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The encoding 'encode-kvgpb' is not supported; must use 'encode-json'.
Why it's wrong here
encode-kvgpb is a valid encoding for GPB (Google Protocol Buffers) in IOS XR telemetry.
- ✓
The collector at 192.168.1.1:57500 is not reachable or the service is down.
Why this is correct
The last error directly states 'Connection refused', meaning the receiver is not accepting connections. The engineer should check the collector's status.
- ✗
The xpath filter is malformed; it should be /interfaces/interface/state.
Why it's wrong here
The xpath '/interfaces-interface-state' is not a standard path but may be accepted depending on the model; however the error is about connection, not filter.
- ✗
The periodic update interval of 500 ms is too fast causing subscription failure.
Why it's wrong here
The subscription state 'Invalid' is not due to update interval; a fast interval might cause high CPU but not invalid state.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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