300-320 Question #278: Real Exam Question with Answer & Explanation

Question

Options

• A6to4 tunnels allow isolated IPv6 domains to be remotely connected over IPv4 networks.
• BManual configuration (scalability) is easier.
• CPoint-to-multipoint automatic tunneling (automatic 6to4) is available.
• DAn infinite number of address spaces are allocated to an IPv6 subnet.
• EGlobally unique IPv4 addresses are not required.

Explanation

6to4 is a tunneling mechanism that encapsulates IPv6 packets inside IPv4 packets, enabling isolated IPv6 islands to communicate over an IPv4 backbone without requiring manual tunnel configuration between every pair (A). It supports automatic point-to-multipoint tunneling: a 6to4 host or router can reach any other 6to4 site automatically by deriving the tunnel endpoint from the embedded IPv4 address in the 6to4 prefix (2002::/16), making it highly scalable (C). Option B is incorrect - 6to4 actually reduces the need for manual configuration, but the mechanism itself (automatic address embedding) is not described as making manual configuration easier. Option D is false; 6to4 allocates a fixed /48 per IPv4 address, not an infinite space. Option E is incorrect because 6to4 requires a globally unique (public) IPv4 address, which is embedded into the 6to4 IPv6 address.

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