350-401 · Question #70
Which IPv6 migration method relies on dynamic tunnels that use the 2002::/16 reserved address space?
The correct answer is B. 6to4. 6to4 is correct because it is specifically designed to use the 2002::/16 address space, where a device's 32-bit IPv4 address is embedded directly into the IPv6 address (forming 2002:[IPv4 in hex]::/48), allowing automatic tunnel creation between IPv6 islands over an IPv4 network
Question
Which IPv6 migration method relies on dynamic tunnels that use the 2002::/16 reserved address space?
Options
- A6RD
- B6to4
- CISATAP
- DGRE
How the community answered
(29 responses)- B93% (27)
- C3% (1)
- D3% (1)
Explanation
6to4 is correct because it is specifically designed to use the 2002::/16 address space, where a device's 32-bit IPv4 address is embedded directly into the IPv6 address (forming 2002:[IPv4 in hex]::/48), allowing automatic tunnel creation between IPv6 islands over an IPv4 network without manual configuration.
6RD (A) is incorrect because it is a provider-managed tunneling method that uses the ISP's own IPv6 prefix (not the reserved 2002::/16 space), essentially an extension of 6to4 but with a service-provider-assigned prefix. ISATAP (C) is wrong because it uses a different addressing scheme (::5EFE:x.x.x.x format) and is designed for tunneling IPv6 within an IPv4 intranet, not using the 2002::/16 range. GRE (D) is incorrect because it creates manually configured point-to-point tunnels with no special reserved IPv6 address space requirements.
Memory Tip: Think "6to4 = 2002" - the number 2002 looks like it bridges two worlds (IPv4 → IPv6), just like 6to4 tunneling bridges the two protocols using that exact prefix.
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