What is the numeric range for the first octet of a class B IPv4 address?

A class B IPv4 address is characterized by its first octet falling within the range of 128 to 191. This classification is part of the IPv4 addressing structure that categorizes addresses into different classes based on the first octet, which helps in determining the size and use of the network. Class B addresses are typically assigned to medium to large-sized networks and can accommodate a significant number of hosts, allowing for up to 65,534 individual hosts within a single network.

The first octet's range is essential for understanding how IP address distribution works across networks. By knowing that class B addresses begin at 128 and end at 191, networking professionals can effectively design and manage their networks, ensuring proper routing and addressing of devices.

This range directly defines how the IPv4 address space is segmented, making it crucial for network engineers and administrators to understand when planning for network architecture and IP address allocation.