Tcp Ip facts

While investigating facts about Tcp Ip, I found out little known, but curios details like:

The internet protocol (IP) starts at version 4 because it was split from a previous protocol (of which 3 early versions were developed during the 1970s) that comprised both what are now TCP and IP, and which was called only TCP. After the split, number 4 was applied to both for consistency

In my opinion, it is useful to put together a list of the most interesting details from trusted sources that I've come across. Here are 1 of the best facts about Tcp Ip I managed to collect.