In Stateless Address Auto-Configuration, what are the first 10 bits of the generated link-local address?

In Stateless Address Auto-Configuration, what are the first 10 bits of the generated link-local address?

• A. 1010 1010 01
• B. 1111 1110 01
• C. 1111 1110 10
• D. 1100 0000 11

Answer: (C)

IPv6 link-local addresses use the prefix FE80::/10. That means the first 10 bits of any link-local address are fixed and equal to 1111111010. FE80 in binary is 11111110 10000000, and taking the first 10 bits from that prefix gives 1111111010. So the first 10 bits are 1111 1110 10, matching the option that shows that sequence. The rest of the address is formed for the interface identifier, but the initial ten bits must always be 1111111010 for link-local scope.

IPv6 link-local addresses use the prefix FE80::/10. That means the first 10 bits of any link-local address are fixed and equal to 1111111010. FE80 in binary is 11111110 10000000, and taking the first 10 bits from that prefix gives 1111111010. So the first 10 bits are 1111 1110 10, matching the option that shows that sequence. The rest of the address is formed for the interface identifier, but the initial ten bits must always be 1111111010 for link-local scope.