https://cloud.google.com/blog/topics/inside-google-cloud/google-cloud-support-engineer-solves-a-tough-dns-case

Google Cloud支持案例。帮助客户解决一个DNS查询失败引出的问题。通过假设，从防火墙、元数据服务器、DNS解析库，网络层。通过调试发现是net.core.rmem_default的配置太小。但通过调整后还是不能正常工作。最后发现是因为LKML的bug，整形溢出问题。

过程很精彩

Google Cloud Blog

A Google Cloud support engineer solves a tough DNS case | Google Cloud Blog

How a Google Cloud support engineer found one customer’s missing DNS packets