楼上好像没有人提到，当时的设计，是为了兼容其它地址格式的网络
下面是 chatgpt 的回答

-why just use a 8-bit octet for part of the ipv4 ip address?
-IPv4 addresses use 8-bit octets to represent each of the four segments of the IP address for historical reasons.

When the Internet Protocol was first developed in the 1970s, it was designed to work on a variety of different types of networks, each with its own addressing scheme. The use of 8-bit octets was a compromise between the different addressing schemes used by the various networks at the time.

Using 8-bit octets made it possible to represent a wide range of addresses in a standardized way that could work across different networks. It also allowed for efficient routing of packets across the internet by using a hierarchical addressing scheme that made it possible to group addresses together into networks and subnetworks.

Over time, the use of 8-bit octets became a widely accepted convention and is still used in IPv4 today, even though it may not be the most efficient or flexible way to represent IP addresses. It is, however, important to note that IPv6, the newer version of the Internet Protocol, uses 128-bit addresses, which allow for a much larger range of possible addresses, making it less likely that we will run out of IP addresses in the future.