Which statement correctly differentiates IPv4 and IPv6 addressing?

• A. IPv4 uses 32-bit addresses; IPv6 uses 128-bit addresses.
• B. IPv4 uses 128-bit addresses; IPv6 uses 32-bit addresses.
• C. IPv4 addresses are written only in decimal; IPv6 addresses are written only in hexadecimal.
• D. IPv4 is newer than IPv6.

Answer: (A)

The main idea tested here is how IPv4 and IPv6 differ in address size and how they’re written. IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses. That huge difference in bit length is what drives the big change in how many unique addresses exist and how they’re represented.

Because IPv4 is 32 bits, there are about 4.3 billion possible addresses, typically written as four decimal numbers separated by dots (for example, 192.0.2.1). IPv6 expands to 128 bits, giving an enormous number of possible addresses, and it’s written as eight groups of four hexadecimal digits separated by colons (for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334). You can also shorten IPv6 addresses by omitting leading zeros and using "::" to compress stretches of zeros.

So the correct statement highlights the fundamental difference in address size: 32-bit for IPv4 and 128-bit for IPv6. The other options mix up the bit sizes, claim absolute notations that aren’t true (IPv4 isn’t only decimal and IPv6 isn’t only hexadecimal in all forms), or state an order of age that isn’t accurate.