Cisco Certified Internetwork Expert (CCIE) 2025 – 400 Free Practice Questions to Pass the Exam

The prefix address of a 6to4 tunnel is determined by the IPv6 configuration applied to the interface. In a 6to4 tunnel, the IPv6 addresses that are assigned to the interface are derived from the IPv4 address of the router. Specifically, the first 48 bits of the IPv6 address are fixed and reserved for 6to4 (2002::/16), while the subsequent 32 bits come from the IPv4 address in its hexadecimal format.

When configuring a 6to4 tunnel, the interface must be set up correctly to include the appropriate IPv6 address that combines the designated prefix with the IPv4 address. This allows the tunnel to encapsulate IPv6 packets within IPv4 for transmission across the IPv4 internet.

Other options, while relevant to networking, do not play a direct role in determining the prefix address for a 6to4 tunnel. Static configuration in the router can set various parameters but does not specifically dictate the prefix for 6to4 tunneling. DHCP server settings typically involve address assignment for dynamic IP addressing, particularly for IPv4, and do not influence a 6to4 tunnel's prefix address. Similarly, the address of the terminating node is part of the connection but is not