The answer is that the encoding should be 'encode-json' or 'encode-gpb' instead of 'encode-kvgpb' for gRPC dial-out. This is because on Cisco IOS-XE, the 'encode-kvgpb' keyword specifies Key-Value Google Protocol Buffers, which is used for native TCP or UDP transports, not for gRPC; gRPC requires either JSON or standard GPB encoding to properly serialize telemetry data over the HTTP/2-based gRPC stream. On the ENCOR 350-401 exam, this question tests your understanding of model-driven telemetry configuration syntax, specifically the encoding mismatch that is a common configuration error in gRPC dial-out setups. The trap is that 'kvgpb' looks similar to 'gpb' but is incompatible with the 'grpc-tcp' receiver protocol, so candidates often overlook this subtle but critical distinction. Memory tip: think "gRPC needs GPB or JSON, not KV-GPB" — the 'KV' stands for key-value, which is a different transport format.
350-401 Python for Network Automation Practice Question
This 350-401 practice question tests your understanding of python for network automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 configures model-driven telemetry on a Cisco IOS-XE device using gRPC dial-out. The subscription configuration snippet is:
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'encoding' should be 'encode-json' or 'encode-gpb' instead of 'encode-kvgpb' for gRPC.
The 'encoding' command uses 'encode-kvgpb' which is incorrect. The correct encoding keyword for gRPC is 'encode-kvgpb'? Actually, in IOS-XE, the encoding for gRPC is 'encode-kvgpb' (Key-Value GPB) or 'encode-json'. However, the command 'encoding encode-kvgpb' is valid. Another issue: The 'receiver' command should specify 'ip address' but the syntax is 'receiver ip address <ip> <port> protocol <protocol>'. That seems correct. Wait, the protocol should be 'grpc-tcp' which is valid. The real issue might be that the subscription uses 'stream yang-push' but the filter xpath is not properly scoped. However, a common mistake is that the 'update-policy periodic' requires a time in seconds, but 500 is valid. Let me think: The major issue is that the 'receiver' command is missing the 'protocol' keyword? Actually, it's there. Hmm. Perhaps the issue is that the encoding 'encode-kvgpb' is not supported for gRPC; it should be 'encode-json' or 'encode-gpb'. In IOS-XE, for gRPC dial-out, the encoding is typically 'encode-json' or 'encode-gpb' (Google Protocol Buffers). 'kvgpb' is a different format. So the correct answer is that 'encode-kvgpb' is invalid; it should be 'encode-json' or 'encode-gpb'.
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.
✓
The 'encoding' should be 'encode-json' or 'encode-gpb' instead of 'encode-kvgpb' for gRPC.
Why this is correct
KVGPB is not a standard encoding for gRPC; JSON or GPB are used.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The 'stream' should be 'yang-notif' instead of 'yang-push'.
Why it's wrong here
yang-push is correct for periodic push updates.
✗
The 'update-policy periodic' value must be between 100 and 1000 milliseconds.
Why it's wrong here
The value is in seconds, and 500 is valid.
✗
The 'receiver' command should specify 'protocol grpc' instead of 'grpc-tcp'.
Why it's wrong here
grpc-tcp is the correct protocol keyword for gRPC over TCP.
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.
Trap categories for this question
Keyword trap
grpc-tcp is the correct protocol keyword for gRPC over TCP.
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.
Python for Network Automation — This question tests Python for Network Automation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The 'encoding' should be 'encode-json' or 'encode-gpb' instead of 'encode-kvgpb' for gRPC. — The 'encoding' command uses 'encode-kvgpb' which is incorrect. The correct encoding keyword for gRPC is 'encode-kvgpb'? Actually, in IOS-XE, the encoding for gRPC is 'encode-kvgpb' (Key-Value GPB) or 'encode-json'. However, the command 'encoding encode-kvgpb' is valid. Another issue: The 'receiver' command should specify 'ip address' but the syntax is 'receiver ip address <ip> <port> protocol <protocol>'. That seems correct. Wait, the protocol should be 'grpc-tcp' which is valid. The real issue might be that the subscription uses 'stream yang-push' but the filter xpath is not properly scoped. However, a common mistake is that the 'update-policy periodic' requires a time in seconds, but 500 is valid. Let me think: The major issue is that the 'receiver' command is missing the 'protocol' keyword? Actually, it's there. Hmm. Perhaps the issue is that the encoding 'encode-kvgpb' is not supported for gRPC; it should be 'encode-json' or 'encode-gpb'. In IOS-XE, for gRPC dial-out, the encoding is typically 'encode-json' or 'encode-gpb' (Google Protocol Buffers). 'kvgpb' is a different format. So the correct answer is that 'encode-kvgpb' is invalid; it should be 'encode-json' or 'encode-gpb'.
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: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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