I'm just wondering because I want to create an Intranet for my dad's company.
Sure, why not.
Most if not all networks use the standard protocols, many of which have been implemented in C++ libraries.
The question you should be asking is:
"Do I have the time, patience and resources to build a network for my dads company?".
Only you can answer that, but good luck anyway.
Can you give me an example of a C++ library for intranets?