What is the total number of addresses in a 32-bit IPv4 address space?

• A. 2,147,483,648 addresses
• B. 4,294,967,296 addresses
• C. 3,000,000,000 addresses
• D. 4,096 addresses

Answer: (B)

IPv4 addresses use 32-bit numbers, so the total number of unique addresses is 2^32. That works out to 4,294,967,296 possible addresses. In dotted-decimal form, these range from 0.0.0.0 to 255.255.255.255. While many addresses are reserved for special uses, the size of the overall address space is 4,294,967,296. So the total count is 4,294,967,296 addresses.