Question 1,754 of 1,389
CCNA Network Infrastructure and Connectivity Practice Question
A network technician configures a Windows 10 PC with a static IPv6 address of 2001:db8:acad:1::100/64 and a default gateway of 2001:db8:acad:2::1. The PC can communicate with other hosts in the 2001:db8:acad:1::/64 subnet, but it cannot access any resources on other subnets, even though IPv4 connectivity through the same network works normally. What is the most likely reason for this issue?
⚠ Common exam trap
Cisco often tests the concept that an IPv6 host will only use a default gateway that is within the same subnet (same /64 prefix) as its own configured IPv6 address, unlike IPv4 where a gateway in a different subnet can still be used if the host has a route to it.
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
✓
The PC's default gateway address is in a different subnet than the PC's IPv6 address.
The PC's IPv6 address is 2001:db8:acad:1::100/64, placing it in the 2001:db8:acad:1::/64 subnet. The configured default gateway is 2001:db8:acad:2::1, which belongs to the 2001:db8:acad:2::/64 subnet. For IPv6, a host will only consider a default gateway on the same link-local or on-link subnet; if the gateway address is not within the same /64 prefix as the host's address, the host cannot send packets to it directly, and all off-subnet traffic fails.
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 PC's default gateway address is in a different subnet than the PC's IPv6 address.
Why this is correct
An IPv6 host only uses a default gateway if it is on the same subnet. Since 2001:db8:acad:2::1 is in a different /64 subnet than the PC's 2001:db8:acad:1::100/64, the host considers the gateway unreachable and cannot send traffic beyond the local link.
- ✗
The PC's IPv6 stack has a corrupted binding that prevents routing.
Why it's wrong here
Corrupted bindings might cause intermittent issues but are not the most likely cause when the configuration shows a clear subnet mismatch. Additionally, the IPv6 stack would have to be specifically damaged to affect only routing while leaving local communication intact.
- ✗
The router's IPv6 routing table does not have a route back to the PC's subnet.
Why it's wrong here
If the router did not have a route back, the PC could still send packets out to the router if the gateway is correct. Here, the PC cannot even reach the gateway because it is misconfigured. Also, IPv4 connectivity works normally, indicating the router has proper connectivity on the link.
- ✗
The DNS server for IPv6 resolution is misconfigured, causing all off-subnet traffic to fail.
Why it's wrong here
DNS problems only prevent name resolution; they do not block direct IP connectivity. If the PC can ping an off-subnet destination's IPv6 address, it would still work. The symptom describes inability to access any resources, not just name-based ones.
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 PC's default gateway address is in a different subnet than the PC's IPv6 address.Correct answer▾
Why this is correct
An IPv6 host only uses a default gateway if it is on the same subnet. Since 2001:db8:acad:2::1 is in a different /64 subnet than the PC's 2001:db8:acad:1::100/64, the host considers the gateway unreachable and cannot send traffic beyond the local link.
✗The PC's IPv6 stack has a corrupted binding that prevents routing.Wrong answer — click to see why▾
Why this is wrong here
This is a less common and less specific cause; the symptom points directly to a misconfigured gateway address in a different subnet.
✗The router's IPv6 routing table does not have a route back to the PC's subnet.Wrong answer — click to see why▾
Why this is wrong here
This option assumes a routing problem on the router, but the scenario indicates the PC cannot send packets to its gateway, which points to host configuration, not routing tables.
✗The DNS server for IPv6 resolution is misconfigured, causing all off-subnet traffic to fail.Wrong answer — click to see why▾
Why this is wrong here
DNS misconfiguration would cause failures when using hostnames, but not for direct IP connectivity tests like pinging a remote IPv6 address.
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
About these practice questions
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 →
Last reviewed: Jun 25, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.