- A
Untrusted
The default role is untrusted, so ND messages are inspected.
- B
Trusted
Why wrong: Trusted is not the default; it must be configured.
- C
Server
Why wrong: Server is a role for DHCP guard, not ND inspection.
- D
Host
Why wrong: Host is a role that can be configured, but not default.
Question 526 of 2,152
Default Interface Role in IPv6 ND Inspection — Untrusted | Cisco CCNP ENARSI 300-410
This 300-410 practice question tests your understanding of ipv6 first hop security. 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.
What is the default role of an interface in IPv6 Neighbor Discovery Inspection when no policy is explicitly applied?
Quick Answer
The answer is untrusted. By default, all interfaces on a Cisco device are assigned the role of untrusted for IPv6 Neighbor Discovery Inspection when no policy is explicitly applied, meaning every incoming ND message on that interface is subject to strict validation checks such as source address verification and reachability testing. This default behavior ensures that no interface is implicitly trusted, forcing the network administrator to consciously designate trusted ports only after verifying the security posture of connected devices. On the Cisco CCNP ENARSI 300-410 exam, this concept tests your understanding of IPv6 First Hop Security fundamentals, often appearing as a straightforward question that traps candidates into assuming a management or uplink interface would be trusted by default. A common memory tip is to think of the word “untrusted” as the default state for all interfaces in ND inspection, just like a locked door that requires a key to open—nothing is trusted until you explicitly apply the “ipv6 nd inspection trust” command.
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
✓
Untrusted
In IPv6 Neighbor Discovery Inspection (NDI), an interface is considered untrusted by default when no policy is explicitly applied. This default ensures that all incoming Neighbor Discovery (ND) messages are subject to validation against the binding table, preventing attacks such as Neighbor Advertisement spoofing and Duplicate Address Detection (DAD) exploitation. Only interfaces explicitly configured with a trust policy bypass this inspection.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Untrusted
Why this is correct
The default role is untrusted, so ND messages are inspected.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Trusted
Why it's wrong here
Trusted is not the default; it must be configured.
- ✗
Server
Why it's wrong here
Server is a role for DHCP guard, not ND inspection.
- ✗
Host
Why it's wrong here
Host is a role that can be configured, but not default.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that all interfaces start as trusted or that a 'host' or 'server' role exists, when in fact the default is untrusted and only two roles (untrusted and trusted) are defined for NDI.
Detailed technical explanation
How to think about this question
IPv6 NDI is part of the IPv6 First Hop Security (FHS) feature set, leveraging the binding table built from DHCPv6 snooping and ND snooping. On an untrusted interface, every ND message (NS, NA, RS, RA) is validated against the binding table; if no binding exists, the packet is dropped. This default prevents rogue devices from injecting false ND messages, a common vector in IPv6 LAN attacks like Neighbor Cache Poisoning.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 300-410 question test?
IPv6 First Hop Security — This question tests IPv6 First Hop Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Untrusted — In IPv6 Neighbor Discovery Inspection (NDI), an interface is considered untrusted by default when no policy is explicitly applied. This default ensures that all incoming Neighbor Discovery (ND) messages are subject to validation against the binding table, preventing attacks such as Neighbor Advertisement spoofing and Duplicate Address Detection (DAD) exploitation. Only interfaces explicitly configured with a trust policy bypass this inspection.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jul 4, 2026
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