How many bits are contained in each field of an IPv6 address?

24 bits per field would produce a total of 192 bits across 8 fields, which exceeds the 128-bit IPv6 address specification.

4 bits is the size of a single hexadecimal digit, not a field; each IPv6 field contains four hex digits, totaling 16 bits per field.

8 bits per field would only produce 64 total bits across 8 fields, which is half the required 128-bit IPv6 address length.

Each of the 8 fields in an IPv6 address is 16 bits long, represented as four hexadecimal digits; multiplying 8 fields by 16 bits yields the full 128-bit IPv6 address size defined in RFC 2460.