Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
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 choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
A usable default router or next-hop route for off-link IPv6 traffic
This is correct because the host needs a next hop to reach remote IPv6 destinations.
B
Distractor review
A NAT rule translating IPv6 to IPv4
This is wrong because normal IPv6 routing does not depend on NAT in this scenario.
C
Distractor review
A VLAN trunk on the host NIC
This is wrong because the symptom is missing off-link routing, not host VLAN trunking.
D
Distractor review
A second global unicast address on the same interface
This is wrong because the host already has a valid IPv6 address and needs reachability information, not a duplicate address.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is to assume that a valid global unicast IPv6 address and prefix length guarantee full IPv6 connectivity. Candidates often overlook the critical role of the default router or next-hop route, which is essential for forwarding packets beyond the local link. This mistake leads to confusion when the host can ping local neighbors but fails to reach remote IPv6 destinations. The trap is reinforced by the fact that IPv6 uses different mechanisms, such as Router Advertisements, to learn default routes, unlike IPv4 where DHCP or manual default gateway configuration is more common. Misunderstanding this can cause incorrect answers in routing and addressing questions.
Technical deep dive
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.
Related practice questions
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
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. In practical terms, the host already knows how to communicate on its own local link, which is why local communication works. But remote IPv6 destinations require a next hop. Without that next hop, the host has no path off the local segment. This is the IPv6 equivalent of a missing default gateway problem in IPv4, but the way hosts learn it often differs. The key point is that local addressing alone is not enough for off-link communication.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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