How many bits are in an IPv4 address?

An IPv4 address consists of 32 bits. This is a fundamental design of the IPv4 protocol, which was developed to identify devices on a network using a unique numerical address. The 32 bits are typically represented as four octets, with each octet consisting of 8 bits. This structure allows for a total of 2^32 distinct addresses, which equals approximately 4.3 billion unique addresses.

The other potential choices do not align with the standard definition of an IPv4 address. For instance, 16 bits would provide only 65,536 unique addresses, which is insufficient for global internet connectivity. Similarly, 64 bits and 128 bits correspond to the sizes used by other protocols, such as IPv6, but are not applicable to IPv4. In summary, the correct understanding of the bit length of an IPv4 address is crucial for networking professionals, as it directly affects address allocation and management in IPv4 networks.