The book TCP-IP Illustrated is the bible. You should buy it at some point. For now, just use this copy. http://www.r-5.org/files/books/computers/internals/net/Richard_Stevens-TCP-IP_Illustrated-EN.pdf. I had a hard copy for a while, but I left it behind with my security team when I graduated. I hope it's getting good use now. Anyway, any time you have a question about a protocol, find it here, and do some Google. Together, you are unstoppable. There are two other books in the series, but this is the book that you will use the most.
Networking is really hard, but hopefully this exposure gave you enough. The biggest takeaway you can have is using Google and RFCs effectively to solve your problems. The good news is that when it comes to network problems, someone has already seen it before and asked the question. And, as the joke goes, it is always a DNS problem.