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300-410 Practice Question: Which TWO statements correctly describe the…
Which TWO statements correctly describe the behavior of automatic 6to4 tunneling? (Choose TWO.)
⚠ Common exam trap
Cisco often tests the distinction between 6to4 (2002::/16) and Teredo (2001::/16), and candidates mistakenly think private IPv4 addresses are acceptable for 6to4 tunnel sources.
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 6to4 prefix is 2002::/16, where the next 32 bits are the IPv4 address of the tunnel source in hexadecimal.
RFC 3056 defines the 6to4 prefix as 2002::/16, and the next 32 bits are the IPv4 address of the tunnel source converted to hexadecimal. This embeds the IPv4 address directly into the IPv6 prefix, allowing automatic tunnel creation without explicit peer configuration.
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 6to4 prefix is 2002::/16, where the next 32 bits are the IPv4 address of the tunnel source in hexadecimal.
Why this is correct
Correct. The 6to4 prefix is 2002::/16, and the IPv4 address is embedded in hex in the next 32 bits.
- ✓
A 6to4 relay router must have an IPv6 route to 2002::/16 pointing to the tunnel interface.
Why this is correct
Correct. The relay router needs a route to 2002::/16 via the tunnel to forward traffic from native IPv6 to 6to4 domains.
- ✗
6to4 tunnels can use private IPv4 addresses as the tunnel source.
Why it's wrong here
Incorrect. 6to4 requires a global, routable IPv4 address because the IPv4 address is embedded in the IPv6 prefix.
- ✗
The 6to4 prefix is 2001::/16, and the IPv4 address is embedded in the interface ID.
Why it's wrong here
Incorrect. 2001::/16 is used for Teredo, not 6to4. The IPv4 address is embedded in the network prefix, not the interface ID.
- ✗
The tunnel interface must be configured with tunnel mode ipv6ip.
Why it's wrong here
Incorrect. The correct tunnel mode for 6to4 is tunnel mode ipv6ip 6to4, not just ipv6ip.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.