What is the hexadecimal format primarily used for in IP addressing?

• A. It is primarily used with IPv6 but can also represent IPv4 addresses in some programs.
• B. It is used exclusively for IPv4 addresses in some routers.
• C. It encodes MAC addresses for IP networks.
• D. It determines subnet masks for private addresses.

Answer: (A)

Hexadecimal notation is used for IPv6 addresses because IPv6 is 128 bits long and is written as eight 16‑bit blocks in hex, separated by colons. This hex representation keeps the long addresses readable and compact, and it allows zero compression to make addresses even shorter when possible. While IPv4 addresses are typically shown as decimal dotted quad, some programs or debugging tools may display IPv4 addresses in hexadecimal, but that isn’t the standard way IPv4 is written. Hexadecimal formats aren’t used to encode MAC addresses in IP networks—the MAC is a separate, link-layer identifier shown in hex, not part of the IP address notation. IPv6 subnetting uses prefix lengths (like /64) rather than a hex mask, so hex isn’t about determining subnet masks in typical practice. So the main use of hexadecimal format in IP addressing is its role in representing IPv6 addresses, with occasional hex display of IPv4 in specialized tools.