# what happens
# IO与中断
# URL 解析
通过 url 解析获取 hostname
// 在浏览器环境中访问 location
> location.host
shanyue.tech
> location.protocal
https
# DNS
解析 hostname 对应的 IP 地址
$ dig shanyue.tech +short
shanyue.netlify.com.
206.189.89.118
$ dig shici.xiange.tech +short
59.110.216.155
# CDN
# UDP
# TCP
# http
# https
#
# 命令
# dig
# nslookup
# host
# ss