Which class of IPv4 addresses does not support subnetting?

Class D IPv4 addresses are designated for multicast purposes and are not used for standard host addressing. Therefore, they do not support subnetting. Subnetting is a technique used in Class A, B, and C addresses to create multiple, smaller networks within a larger network by borrowing bits from the host portion of the address to create more network addresses. Each of these classes can be divided into subnets to optimize routing and enhance network organization.

In contrast, Class D’s primary function is to send packets to a group of devices (multicast), rather than addressing them individually. Since Class D addresses do not involve hosts in the conventional sense and are not structured for host identification like the other classes, subnetting is not applicable. This is why Class D is the correct answer to the question regarding which class does not support subnetting.