number of bits used by ipv6 address

Answer 1

An IPv6 address has 128 bits. This is because an IPv6 address is hexadecimal (base 16; values represented from 0 - F). Because an IPv6 address has 8 groups of 4 hexidecimal values and each hexidecimal value has 4 bits, we have 128 bits in total.

A bit is binary, or base 2. Because base 16 (hexideicmal) is 2 to the fourth power, we have 4 bits for every hexidecimal value.

Note: Even if most of an IPv6 address is 0's, it still will only ever use 128 bits.