How many bits are in a standard IPv4 address?

• A. 16 bits
• B. 32 bits
• C. 64 bits
• D. 128 bits

Answer: (B)

IPv4 addresses are 32 bits long. An address is four 8-bit numbers called octets, usually written in dotted decimal as a.b.c.d with each value ranging from 0 to 255. Because 8 bits per octet times four octets equals 32 bits, there are 2^32 possible addresses (about 4.29 billion). This length is what defines the IPv4 format, while newer schemes use longer lengths (like 128 bits in IPv6).