DNS学习:
https://www.ze3kr.com/2016/12/domain-name-system/
http://blog.csdn.net/yipiankongbai/article/details/25031461
http://blog.csdn.net/yxwmzouzou/article/details/46643609
IP地址学习:
http://blog.csdn.net/u013018721/article/details/38332703
http://www.cnblogs.com/JuneWang/p/3917697.html