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300-410 Practice Question: Which loop prevention mechanism is inherent to…
Which loop prevention mechanism is inherent to 6to4 tunneling?
⚠ Common exam trap
Cisco often tests the distinction between generic loop prevention mechanisms (like TTL or split horizon) and the specific, inherent validation unique to 6to4 tunneling, leading candidates to overlook the embedded IPv4 address check.
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
✓
Embedded IPv4 address validation
6to4 tunneling uses an embedded IPv4 address in the IPv6 prefix (2002::/16) to automatically derive the tunnel destination. This inherent validation prevents routing loops by ensuring that a 6to4 router only accepts packets whose source IPv4 address matches the embedded address in the IPv6 source prefix, rejecting mismatched or spoofed traffic that could cause loops.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Split horizon
Why it's wrong here
Split horizon is a routing protocol mechanism, not specific to 6to4.
- ✗
Reverse path forwarding (RPF) check
Why it's wrong here
RPF is used for unicast reverse path forwarding, not a built-in 6to4 mechanism.
- ✓
Embedded IPv4 address validation
Why this is correct
6to4 validates that the source IPv6 address's embedded IPv4 matches the tunnel source to prevent spoofing and loops.
- ✗
TTL decrement
Why it's wrong here
TTL decrement is a general mechanism, not specific to 6to4 loop prevention.
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JA
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.