DNSLookupGUI
DNS协议的官方规范文档
https://tools.ietf.org/html/rfc1035
网上有本书《Network Programming In Java》，书没有资源，但是源代码可以参考
http://www.cs.odu.edu/~cs772/sourcecode/JavaNP/ManningJNP/NSLookup.java
http://www.cs.odu.edu/~cs772/sourcecode/JavaNP/ManningJNP/DNSQuery.java
http://www.cs.odu.edu/~cs772/sourcecode/JavaNP/ManningJNP/DNSInputStream.java
http://www.cs.odu.edu/~cs772/sourcecode/JavaNP/ManningJNP/DNS.java