The answer is that setting the Accept header to application/json instead of application/yang-data+json causes the RESTCONF server to return a 406 Not Acceptable error. This occurs because RESTCONF, as defined in RFC 8040, mandates that all media types use the application/yang-data+json format for request and response bodies; the generic application/json type is not recognized by the server as a valid representation of YANG-encoded data. On the CCNA 200-301 v2 exam, this tests your understanding of RESTCONF’s strict media-type negotiation, often appearing in automation questions where you must construct GET and PATCH requests with proper URIs—like percent-encoding the slash in GigabitEthernet0%2F1—and the correct Accept header. A common trap is assuming any JSON format works, but the server rejects it outright. Remember the mnemonic: “YANG data needs YANG headers” to avoid the 406 snag.
CCNA AI and Network Operations Practice Question
This 200-301 practice question tests your understanding of ai and network operations. 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.
Network Topology
You are connected to R1 (192.0.2.1/24, management IP). The network team needs to automate interface configuration using RESTCONF. Construct a valid RESTCONF GET request to retrieve the operational status of GigabitEthernet0/1 using the ietf-interfaces YANG module, and a PATCH request to set the description of that interface to 'Link to R2' using the Cisco-IOS-XE-native YANG module. Identify the error that occurs if the Accept header is set to application/json instead of application/yang-data+json.
R1#show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
ip address 10.0.0.1 255.255.255.252
duplex auto
speed auto
media-type rj45
!
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 192.0.2.1 YES NVRAM up up
GigabitEthernet0/1 10.0.0.1 YES NVRAM up up
Loopback0 203.0.113.1 YES NVRAM up up
A
The server returns a 406 Not Acceptable error because RESTCONF requires the Accept header to be 'application/yang-data+json'.
RESTCONF uses the media type 'application/yang-data+json' for JSON encoding. Setting Accept to 'application/json' violates the RESTCONF specification, causing the server to respond with a 406 Not Acceptable error.
B
The server returns a 400 Bad Request error because the Accept header must be 'application/json' for RESTCONF.
Why wrong: This is incorrect because RESTCONF does not use 'application/json' as the standard media type; it uses 'application/yang-data+json'. A 400 error indicates a malformed request, not a content negotiation issue.
C
The server returns a 415 Unsupported Media Type error because the Accept header is set incorrectly.
Why wrong: This is incorrect because 415 Unsupported Media Type is used when the Content-Type (request body format) is unsupported, not the Accept header. The Accept header issue results in a 406 error.
D
The server returns a 200 OK response but ignores the Accept header and returns data in XML format.
Why wrong: This is incorrect because RESTCONF servers enforce content negotiation; an invalid Accept header results in an error, not a fallback to XML. The server will not ignore the header.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The server returns a 406 Not Acceptable error because RESTCONF requires the Accept header to be 'application/yang-data+json'.
The correct base URI for RESTCONF on Cisco IOS-XE is https://<device-ip>/restconf/data. For the ietf-interfaces module, the YANG path is /ietf-interfaces:interfaces/interface=GigabitEthernet0%2F1 (note the percent-encoded slash in the key). For the Cisco-IOS-XE-native module, the path is /Cisco-IOS-XE-native:native/interface/GigabitEthernet=0%2F1/description. The Accept header must be 'application/yang-data+json'; using 'application/json' returns a 406 Not Acceptable error. The PATCH request body must contain the new description in JSON format. Failing to percent-encode the interface name will result in an invalid URI.
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 server returns a 406 Not Acceptable error because RESTCONF requires the Accept header to be 'application/yang-data+json'.
Why this is correct
RESTCONF uses the media type 'application/yang-data+json' for JSON encoding. Setting Accept to 'application/json' violates the RESTCONF specification, causing the server to respond with a 406 Not Acceptable error.
Related concept
Static NAT maps one inside address to one outside address.
✗
The server returns a 400 Bad Request error because the Accept header must be 'application/json' for RESTCONF.
Why it's wrong here
This is incorrect because RESTCONF does not use 'application/json' as the standard media type; it uses 'application/yang-data+json'. A 400 error indicates a malformed request, not a content negotiation issue.
✗
The server returns a 415 Unsupported Media Type error because the Accept header is set incorrectly.
Why it's wrong here
This is incorrect because 415 Unsupported Media Type is used when the Content-Type (request body format) is unsupported, not the Accept header. The Accept header issue results in a 406 error.
✗
The server returns a 200 OK response but ignores the Accept header and returns data in XML format.
Why it's wrong here
This is incorrect because RESTCONF servers enforce content negotiation; an invalid Accept header results in an error, not a fallback to XML. The server will not ignore the header.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The server returns a 406 Not Acceptable error because RESTCONF requires the Accept header to be 'application/yang-data+json'.Correct answer▾
Why this is correct
RESTCONF uses the media type 'application/yang-data+json' for JSON encoding. Setting Accept to 'application/json' violates the RESTCONF specification, causing the server to respond with a 406 Not Acceptable error.
✗The server returns a 400 Bad Request error because the Accept header must be 'application/json' for RESTCONF.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: RESTCONF requires 'application/yang-data+json', not 'application/json'.
Why candidates choose this
Candidates might think 'application/json' is acceptable because JSON is commonly used, but RESTCONF mandates a specific media type.
✗The server returns a 415 Unsupported Media Type error because the Accept header is set incorrectly.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: 415 relates to Content-Type, not Accept. Accept errors yield 406.
Why candidates choose this
Candidates may confuse Accept and Content-Type headers, thinking both cause 415 errors.
✗The server returns a 200 OK response but ignores the Accept header and returns data in XML format.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: RESTCONF does not silently fall back; it returns a 406 error.
Why candidates choose this
Candidates might assume the server is lenient and will respond with a default format, but RESTCONF is strict about media types.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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 200-301 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 200-301 NAT questions on configuration and troubleshooting.
AI and Network Operations — This question tests AI and Network Operations — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The server returns a 406 Not Acceptable error because RESTCONF requires the Accept header to be 'application/yang-data+json'. — The correct base URI for RESTCONF on Cisco IOS-XE is https://<device-ip>/restconf/data. For the ietf-interfaces module, the YANG path is /ietf-interfaces:interfaces/interface=GigabitEthernet0%2F1 (note the percent-encoded slash in the key). For the Cisco-IOS-XE-native module, the path is /Cisco-IOS-XE-native:native/interface/GigabitEthernet=0%2F1/description. The Accept header must be 'application/yang-data+json'; using 'application/json' returns a 406 Not Acceptable error. The PATCH request body must contain the new description in JSON format. Failing to percent-encode the interface name will result in an invalid URI.
What should I do if I get this 200-301 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 200-301 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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