The correct way to access the IP address is `data['ietf-interfaces:interfaces']['interface'][0]['ipv4']['address'][0]['ip']`, which returns '192.168.1.1'. This is necessary because RESTCONF returns telemetry data as a deeply nested JSON dictionary, where each key corresponds to a YANG data model node, and lists like `interface` and `address` require index-based access. On the ENCOR 350-401 exam, this tests your ability to parse telemetry JSON responses from Cisco IOS-XE devices, a common task for automation and programmability topics. A frequent trap is forgetting that `interface` is a list even when only one interface exists, or mistaking the module-prefixed key `ietf-interfaces:interfaces` for a simple `interfaces`. To remember the path, think of it as drilling down through the YANG container hierarchy: module, interface list, first entry, IPv4 container, address list, first entry, then the IP leaf.
CCNP Model-Driven Telemetry Practice Question
This 350-401 practice question tests your understanding of model-driven telemetry. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An engineer retrieves telemetry data from a Cisco IOS-XE device using RESTCONF and receives the following response:
The JSON response is nested. To access the IP address, you need to navigate through the dictionary: data['ietf-interfaces:interfaces']['interface'][0]['ipv4']['address'][0]['ip']. This returns '192.168.1.1'.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Missing the list index for 'interface'; it should be [0].
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
Model-Driven Telemetry — This question tests Model-Driven Telemetry — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: data['ietf-interfaces:interfaces']['interface'][0]['ipv4']['address'][0]['ip'] — The JSON response is nested. To access the IP address, you need to navigate through the dictionary: data['ietf-interfaces:interfaces']['interface'][0]['ipv4']['address'][0]['ip']. This returns '192.168.1.1'.
What should I do if I get this 350-401 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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