curl -o /dev/null -s -w time_namelookup:"t"%{time_namelookup}"n"time_connect:"tt"%{time_connect}"n"time_appconnect:"t"%{time_appconnect}"n"time_pretransfer:"t"%{time_pretransfer}"n"time_starttransfer:"t"%{time_starttransfer}"n"time_total:"tt"%{time_total}"n"time_redirect:"tt"%{time_redirect}"n" https://www.baidu.com
调试dns解析响应速度
dig www.baidu.com ns +trace
dig www.baidu.com a