Hello, In the past when Ive been confused about certain networking fundamentals I always went to professor messer to find an answer. He makes very easy to follow videos that follow the CompTia syllabuses from many of their certificates. A lot of these videos however are good to just go back to relearn certain concepts. A find myself often going back to his videos about DNS and Routing protocols because they can get confusing sometimes. https://www.professormesser.com/