CCNA Network Infrastructure and Connectivity Practice Question
An IPv6 host successfully reaches neighbors on its local segment, but it cannot reach remote IPv6 destinations. The host has a global unicast address and a correct prefix length. Which missing item is the strongest suspect?
⚠ Common exam trap
Don't confuse local connectivity success with overall network configuration correctness. Always check for a default route when remote communication fails.
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
✓
A usable default router or next-hop route for off-link IPv6 traffic
The strongest suspect is the absence of a usable default router learned through IPv6 router advertisements or equivalent configuration. While local connectivity works because the host can communicate on its own link, remote IPv6 destinations require a next hop off the local segment. Option B is wrong because IPv6-to-IPv4 NAT is unnecessary for native IPv6 communication and would not be the primary cause of off-link failure. Option C is wrong because a VLAN trunk on the host NIC is for carrying multiple VLANs, not for enabling off-link routing. Option D is wrong because a second global unicast address does not provide a default route; it only adds another local address.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A usable default router or next-hop route for off-link IPv6 traffic
Why this is correct
IPv6 hosts on a local segment can communicate with neighbors using Neighbor Discovery (ND) and link-local addresses, but any traffic destined beyond that segment must be forwarded by a router. Without a default router learned via ICMPv6 Router Advertisement or a manually configured static route, the host has no way to choose a next hop for off-link destinations. Thus the host would successfully reach on-link neighbors yet fail to reach anything outside the local segment.
- ✗
A NAT rule translating IPv6 to IPv4
Why it's wrong here
IPv6 was designed to restore end-to-end connectivity without relying on NAT; in normal native IPv6 environments, routing uses global unicast addresses directly. A NAT rule that translates IPv6 to IPv4 would be an unnecessary and complex workaround, and it would not help the host reach off-link IPv6 destinations unless that IPv4 path itself is routed. Since the host already reaches neighbors using IPv6, the missing element is not address translation but a route to a default gateway.
When this WOULD be correct
In a question where a network is transitioning from IPv4 to IPv6 and requires NAT64 to allow IPv6 hosts to communicate with IPv4 servers, a NAT rule translating IPv6 to IPv4 would be the correct answer. The question would specify that IPv6 hosts need to access IPv4 resources, making NAT essential.
- ✗
A VLAN trunk on the host NIC
Why it's wrong here
VLAN trunking is a Layer 2 feature used to carry multiple VLANs over a single switch link, typically between switches or to a router-on-a-stick. An end host NIC rarely requires trunking, and the symptom described is unrelated to VLAN tagging because it concerns Layer 3 reachability. Even if the NIC were configured with a trunk, that would not provide a default route or next hop for off-link IPv6 packets.
When this WOULD be correct
In a different scenario where the question specifies that a host is configured to communicate with multiple VLANs and needs to reach devices on different VLANs, a misconfigured VLAN trunk could indeed prevent communication with remote devices. In such a case, the correct answer would focus on VLAN configurations affecting Layer 3 connectivity.
- ✗
A second global unicast address on the same interface
Why it's wrong here
Adding a second global unicast address to the same interface only provides an additional source or destination identifier for that interface; it does not install any route or gateway information into the host's IPv6 routing table. The host still lacks a default route for off-link traffic, and the existing address already satisfies the requirement of having a valid IPv6 source address. Therefore, a duplicate address does not solve the described reachability problem.
When this WOULD be correct
In a different scenario where a question asks about the configuration of multiple global unicast addresses on an interface, and the context involves load balancing or specific routing requirements, having a second global unicast address could be correct if it allows for proper routing or redundancy in a multi-homed setup.
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.
✓A usable default router or next-hop route for off-link IPv6 trafficCorrect answer▾
Why this is correct
IPv6 hosts on a local segment can communicate with neighbors using Neighbor Discovery (ND) and link-local addresses, but any traffic destined beyond that segment must be forwarded by a router. Without a default router learned via ICMPv6 Router Advertisement or a manually configured static route, the host has no way to choose a next hop for off-link destinations. Thus the host would successfully reach on-link neighbors yet fail to reach anything outside the local segment.
✗A NAT rule translating IPv6 to IPv4Wrong answer — click to see why▾
Why this is wrong here
IPv6 does not require NAT to reach remote destinations; native IPv6 routing uses global unicast addresses and routing protocols. NAT is used for IPv4 address conservation and is not a standard component of IPv6 connectivity.
★ When this WOULD be the correct answer
In a question where a network is transitioning from IPv4 to IPv6 and requires NAT64 to allow IPv6 hosts to communicate with IPv4 servers, a NAT rule translating IPv6 to IPv4 would be the correct answer. The question would specify that IPv6 hosts need to access IPv4 resources, making NAT essential.
Why candidates choose this
Students familiar with IPv4 NAT might assume a similar translation is needed for IPv6, but IPv6 has a vast address space and does not rely on NAT for basic off-link communication.
✗A VLAN trunk on the host NICWrong answer — click to see why▾
Why this is wrong here
VLAN trunking is a switch feature used to carry multiple VLANs over a single link, not a host configuration for routing. The host's inability to reach remote destinations is a routing issue, not a VLAN trunking problem.
★ When this WOULD be the correct answer
In a different scenario where the question specifies that a host is configured to communicate with multiple VLANs and needs to reach devices on different VLANs, a misconfigured VLAN trunk could indeed prevent communication with remote devices. In such a case, the correct answer would focus on VLAN configurations affecting Layer 3 connectivity.
Why candidates choose this
A test-taker might confuse VLAN trunking with the need for a default gateway, especially if they recall that VLANs separate broadcast domains and routing is needed between them.
✗A second global unicast address on the same interfaceWrong answer — click to see why▾
Why this is wrong here
Adding a second global unicast address does not provide a default route or next-hop information. The host already has a valid address; the missing element is a route to off-link destinations, not additional addresses.
★ When this WOULD be the correct answer
In a different scenario where a question asks about the configuration of multiple global unicast addresses on an interface, and the context involves load balancing or specific routing requirements, having a second global unicast address could be correct if it allows for proper routing or redundancy in a multi-homed setup.
Why candidates choose this
Some might think that multiple addresses could help with reachability, but IPv6 hosts can have multiple addresses (e.g., privacy extensions) without affecting routing. The core issue remains the lack of a default router.
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?”
Visual reference
Go deeper
Related to this question
Learn chapter
IPv4 Addressing and Address Classes
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
Key term
NIC
A NIC is a hardware component that connects a computer to a network, enabling communication over wired or wireless media.
About these practice questions
One of 1,389 original 200-301 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.