The answer is the absence of a usable default router or next-hop route for off-link IPv6 traffic. When an IPv6 host can successfully reach neighbors on its local segment but cannot reach remote destinations, it indicates that the host lacks a valid default gateway learned through IPv6 router advertisements or static configuration. Local connectivity works because the host uses Neighbor Discovery Protocol for on-link communication, but off-link traffic requires a router to forward packets beyond the local subnet. On the CCNA 200-301 v2 exam, this scenario tests your understanding of IPv6 addressing and the critical role of the default router in global unicast communication. A common trap is assuming a second global unicast address or NAT would solve the issue, but neither provides a routing path. Remember the memory tip: “Local works, remote fails? Check the default route—no router, no reach.”
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: iPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.. 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 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?
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 VLANtrunk 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.
Key principle: IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.
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
This is correct because the host needs a next hop to reach remote IPv6 destinations.
Related concept
IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.
✗
A NAT rule translating IPv6 to IPv4
Why it's wrong here
This is wrong because normal IPv6 routing does not depend on NAT in this scenario.
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
This is wrong because the symptom is missing off-link routing, not host VLAN trunking.
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 VLANtrunk 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
This is wrong because the host already has a valid IPv6 address and needs reachability information, not a duplicate address.
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
This is correct because the host needs a next hop to reach remote IPv6 destinations.
✗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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Don't confuse local connectivity success with overall network configuration correctness. Always check for a default route when remote communication fails.
Trap categories for this question
Scenario analysis trap
This is wrong because normal IPv6 routing does not depend on NAT in this scenario.
Detailed technical explanation
How to think about this question
IPv6 addressing and routing require more than just a valid global unicast address and prefix length for full connectivity. While the host can communicate with neighbors on the local link using link-local addresses and neighbor discovery protocols, reaching remote IPv6 destinations depends on having a default route or next-hop router. This default router is typically learned through IPv6 Router Advertisements (RAs) sent by routers on the local segment or configured manually. Without this next-hop information, the host cannot forward packets beyond its local network segment.
The decision process for IPv6 routing on a host involves first checking if the destination is on-link using the prefix and prefix length. If the destination is off-link, the host forwards the packet to the default router. If no default router is configured or learned, the host drops the packet because it lacks a path to remote networks. This behavior mirrors IPv4’s default gateway concept but relies on ICMPv6 messages and neighbor discovery rather than DHCP or manual configuration alone.
A common exam trap is assuming that having a global unicast address guarantees full IPv6 connectivity. Many candidates overlook the necessity of a default router or next-hop route, focusing only on address configuration. In practice, a host can ping local neighbors but fail to reach external IPv6 sites if router advertisements are missing or the default route is absent. Understanding this distinction is critical for troubleshooting and for answering CCNA questions accurately.
KKey Concepts to Remember
IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.
A global unicast IPv6 address and correct prefix length alone do not enable communication with remote IPv6 networks without a default route.
IPv6 Router Advertisements provide hosts with default router information necessary for off-link packet forwarding.
Neighbor Discovery Protocol enables local link communication but does not replace the need for a default router for remote access.
Without a usable default router, IPv6 hosts can reach local neighbors but cannot route traffic to external IPv6 destinations.
The absence of a default router in IPv6 is analogous to a missing default gateway in IPv4 routing.
Hosts determine if a destination is on-link using the prefix and prefix length before deciding to forward packets to a next hop.
IPv6 routing decisions on hosts depend on both address configuration and routing information learned dynamically or configured statically.
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
IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.
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.
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 iPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 200-301 question wrong?
Review iPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
IPv6 hosts require a default router or next-hop route to forward packets to off-link destinations beyond the local segment.
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