What is the binary bit pattern of the first octet of a class D IPv4 address?

In a Class D IPv4 address, the first octet is specifically designated for multicast addresses. The defining characteristic of Class D addresses is that the first four bits of the first octet must be set to 1110. This establishes the range of addresses that belong to Class D, which begins at 224.0.0.0 and ends at 239.255.255.255.

The first four bits being 1110 allows for a total of 16 different combinations in the remaining four bits (represented as xxxx), which can vary from 0000 to 1111. This is how multicast addresses are generated within this range. Thus, the binary bit pattern of the first octet for a Class D IPv4 address is accurately represented as 1110xxxx.

This pattern differentiates Class D addresses from other classes, where Class A and Class B have different leading bits. Classes A, B, and C have specific binary patterns starting with 0, 10, and 110 respectively, distinguishing them from the multicast-focused Class D.