300000km*9/1000 = 2700km 算了下觉得不太可能是 ip:host 一对一
然后搜了一下:
Source:
https://www.quora.com/How-is-Google-Public-DNS-able-to-maintain-such-a-low-ping```
IP addresses can be shared among many servers. This is usually done through something called BGP anycast that's really only used by large networks like Google, ISPs and internet backbone providers.
BGP stands for Border Gateway Protocol and is a system that describes how traffic flows around these large global networks. Anycast is a subsystem that allows for multiple servers or regions to "announce" the same IP address. This way, any request that you send to that IP address will receive a response from the closest and/or fastest server to you.
This is used often with DNS and CDN services so that all the servers share the same IP address and users can be anywhere in the world and automatically reach the closest server for them.
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