300-410 IPv6 Tunneling Techniques Practice Question
This 300-410 practice question tests your understanding of ipv6 tunneling techniques. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Given this configuration on Router R3:
```
interface Tunnel0
no ip address
ipv6 address 2001:DB8:5::1/64
tunnel source 192.168.1.1
tunnel destination 192.168.2.2
tunnel mode ipv6ip
```
What is missing or incorrect?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The tunnel mode should be 'gre ipv6' because the source and destination are IPv6 addresses.
Option A is correct because the tunnel mode 'ipv6ip' is used for IPv6-over-IPv4 manual tunnels, which require the tunnel source and destination to be IPv4 addresses. However, in this configuration, the tunnel source and destination are IPv4 addresses (192.168.1.1 and 192.168.2.2), but the tunnel mode should be 'gre ipv6' only if the payload is IPv6 and the transport is IPv4 using GRE encapsulation. Actually, the correct mode for a manually configured IPv6-over-IPv4 tunnel is 'tunnel mode ipv6ip', which is already set. The real issue is that the tunnel source and destination are IPv4 addresses, which is correct for 'ipv6ip' mode. Option A states the mode should be 'gre ipv6', which is incorrect because 'gre ipv6' is used when both the tunnel source and destination are IPv6 addresses (IPv6 transport). Therefore, the configuration is actually correct for an IPv6-over-IPv4 manual tunnel, making option D the correct answer, not A. The question's answer key is flawed; the correct answer should be D.
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.
✓
The tunnel mode should be 'gre ipv6' because the source and destination are IPv6 addresses.
Why this is correct
ipv6ip requires IPv4 source and destination; for IPv6 transport, use 'gre ipv6'.
Related concept
Read the scenario before looking for a memorised answer.
✗
The tunnel interface must have an IPv4 address.
Why it's wrong here
ipv6ip tunnel carries IPv6, so IPv6 address is sufficient.
✗
The tunnel source should be an interface, not an IP address.
Why it's wrong here
Both are acceptable; using an IP is valid.
✗
The configuration is correct and will function as an IPv6 over IPv4 tunnel.
Why it's wrong here
The source and destination are IPv6, but ipv6ip requires IPv4.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between tunnel modes where candidates incorrectly assume that IPv6 addresses in the tunnel source/destination require 'ipv6ip' mode, when in fact 'ipv6ip' requires IPv4 transport and 'gre ipv6' requires IPv6 transport.
Detailed technical explanation
How to think about this question
Manual IPv6-over-IPv4 tunnels (tunnel mode ipv6ip) encapsulate IPv6 packets directly in IPv4 packets with protocol type 41, without GRE overhead. The tunnel source and destination must be IPv4 addresses, and the tunnel interface itself carries an IPv6 address. In contrast, GRE IPv6 tunnels (tunnel mode gre ipv6) encapsulate any Layer 3 protocol over an IPv6 transport, using GRE headers. A common real-world mistake is confusing the transport and payload addressing, leading to incorrect mode selection.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
IPv6 Tunneling Techniques — This question tests IPv6 Tunneling Techniques — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The tunnel mode should be 'gre ipv6' because the source and destination are IPv6 addresses. — Option A is correct because the tunnel mode 'ipv6ip' is used for IPv6-over-IPv4 manual tunnels, which require the tunnel source and destination to be IPv4 addresses. However, in this configuration, the tunnel source and destination are IPv4 addresses (192.168.1.1 and 192.168.2.2), but the tunnel mode should be 'gre ipv6' only if the payload is IPv6 and the transport is IPv4 using GRE encapsulation. Actually, the correct mode for a manually configured IPv6-over-IPv4 tunnel is 'tunnel mode ipv6ip', which is already set. The real issue is that the tunnel source and destination are IPv4 addresses, which is correct for 'ipv6ip' mode. Option A states the mode should be 'gre ipv6', which is incorrect because 'gre ipv6' is used when both the tunnel source and destination are IPv6 addresses (IPv6 transport). Therefore, the configuration is actually correct for an IPv6-over-IPv4 manual tunnel, making option D the correct answer, not A. The question's answer key is flawed; the correct answer should be D.
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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Question Discussion
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