刚才访问 GitHub 出现异常,本来想上 Twitter 看一下状态。发现 Twitter 也上不去。然后 search 了一下发现。

GitHub Status (@githubstatus) October 21, 2016
Our DNS provider is under a DDos attack. Causing connectivity issues for our webpage. Filtering of Inbox emails has not been affected.

原因大概是上游的 dns 服务提供商受到大规模的 DDos 攻击,导致无法通过域名正常访问