http://www.linuxidc.com/Linux/2014-02/96167.htm

http://www.askmaclean.com/archives/dns%E8%AE%BE%E7%BD%AE%E5%BC%95%E8%B5%B7%E7%9A%84%E7%99%BB%E5%BD%95%E5%BB%B6%E8%BF%9F.html

http://www.itpub.net/thread-1508596-1-1.html

http://www.cnblogs.com/kerrycode/p/4164838.html

http://53934616.blog.163.com/blog/static/537677232011464593393/

http://blog.csdn.net/huoyin/article/details/40679877