http://tool.chinaz.com/dns/

# 搜索以下域名的A记录
13.229.188.59 github.com
13.250.162.133 codeload.github.com
75.126.215.88 github.global.ssl.fastly.net

windows

C:\windows\system32\drivers\etc\hosts
ipconfig /flushdns

linux

/etc/hosts
nscd -i hosts