B 站 经常打不开，多个宽带下都有 这种情况
ping 主域名 会有超时情况
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Request timed out.
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Request timed out.
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=59ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=57ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=59ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Request timed out.
Request timed out.
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50
Reply from 117.21.179.20: bytes=32 time=58ms TTL=50