What was the biggest problem with the earliest version of the Internet in the late 1960s?

The biggest problem with the earliest version of the Internet in the late 1960s was that networks couldn't talk to each other. This issue arose primarily because different networks operated using different protocols, which hindered their ability to share data and communicate effectively. The solution to this problem led to the development of protocols that enabled interoperability between various networks, which was essential for creating a more cohesive and functional Internet. This foundational challenge was crucial in shaping the evolution of networking standards, ultimately leading to the integration of the various systems we rely on today.

The other options address issues that may have been relevant in different contexts or later stages of technological development, but the inability of disparate networks to communicate was a fundamental roadblock that needed to be addressed in the very early days of the Internet.