refrences:
http://man7.org/linux/man-pages/man5/resolv.conf.5.html
注:
1. nameserver 最多3个
2. search 作主域名列表，形成完整FQDN
www
ww.w
www.
3. host -a domain
CentOS7 /etc/resolv.conf
原文：https://www.cnblogs.com/leesirc/p/11576124.html
