The IP address 221.1.2.3 belongs to Class C.
Here's a breakdown of the IPv4 address classes:
- Class A: 1.0.0.0 to 126.255.255.255
- Class B: 128.0.0.0 to 191.255.255.255
- Class C: 192.0.0.0 to 223.255.255.255
- Class D: 224.0.0.0 to 239.255.255.255 (used for multicast)
Since 221 falls within the range for Class C (192-223), the answer is Class C.