Which of the following statements about IPv4 address space is true?

• A. It uses 64-bit addresses
• B. It uses 32-bit addresses divided into four octets
• C. It uses 128-bit addresses
• D. It uses 16-bit addresses

Answer: (B)

The main concept here is that IPv4 uses 32-bit addresses, organized as four octets. Each octet is 8 bits, so together they form a 32-bit address. That’s why IPv4 addresses are commonly written in dotted decimal notation, with each octet ranging from 0 to 255, like 192.168.0.1. This structure yields about 4.29 billion unique addresses (2^32).

Why the other statements aren’t correct: 64-bit addresses would provide far more addresses than IPv4 uses. 128-bit addresses are used by IPv6, not IPv4. 16-bit addresses would give only 65,536 possibilities, which is far too small for IPv4.