Which statement best describes IPv4 versus IPv6 addressing?

Which statement best describes IPv4 versus IPv6 addressing?

• A. IPv4 uses 32-bit addresses, IPv6 uses 128-bit addresses; IPv4 loopback is 127.0.0.1.
• B. IPv4 uses 64-bit addresses; IPv6 uses 128-bit addresses.
• C. IPv4 loopback is 255.255.255.255.
• D. IPv4 and IPv6 addresses are both commonly written in decimal dotted notation.

Answer: (A)

IPv4 and IPv6 differ mainly in address size and how they’re written. IPv4 uses 32-bit addresses and is written as four decimal numbers separated by dots (for example, 192.0.2.1). IPv6 uses 128-bit addresses and is written as eight groups of hexadecimal digits separated by colons (for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The IPv4 loopback address is 127.0.0.1, which is a single-host address within the 32-bit IPv4 space. The statement aligns with these facts, while the other options are incorrect: one incorrectly states IPv4 uses 64-bit addresses, another gives an incorrect loopback address for IPv4, and another claims both protocols share decimal dotted notation, which is not true for IPv6.

IPv4 and IPv6 differ mainly in address size and how they’re written. IPv4 uses 32-bit addresses and is written as four decimal numbers separated by dots (for example, 192.0.2.1). IPv6 uses 128-bit addresses and is written as eight groups of hexadecimal digits separated by colons (for example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334). The IPv4 loopback address is 127.0.0.1, which is a single-host address within the 32-bit IPv4 space. The statement aligns with these facts, while the other options are incorrect: one incorrectly states IPv4 uses 64-bit addresses, another gives an incorrect loopback address for IPv4, and another claims both protocols share decimal dotted notation, which is not true for IPv6.