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I'm pinging (from Europe) an IP belonging to Firebase's CDN via this command: ping 151.101.65.195

I get the following result:

PING 151.101.65.195 (151.101.65.195) 56(84) bytes of data.
64 bytes from 151.101.65.195: icmp_seq=1 ttl=57 time=6.78 ms
64 bytes from 151.101.65.195: icmp_seq=2 ttl=57 time=6.70 ms
...

6-7 ms sounds too low to me between Europe and this IP, which — according to IP geolocation websites — resides in San Francisco.

As part of another experiment, I logged into a VPS located in the east coast of US. Ping was reporting around 1 ms for the same IP.

Assuming that IP geolocation websites are right and ping results are not cached by the ISPs, the reported numbers are so low that they seem to violate the speed of light, so I must be overlooking something.

The only explanation I can think of (apart from misreading ping's output) is that maybe the IP is somehow specific and resolves to different computers depending on where the request is initiated from. This violates my assumptions about global IP addresses being unique though. Could somebody shed some light here please?

Both computers in the above experiments are running Ubuntu.

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There are indeed IP adresses, who have geo-specific routing: The trick is that the BGP announcements are by design not consistent around the globe, creating non-unique IP adresses without trashing routing tables. This is usually called "anycast" routing.

Well-known examples of anycast usage are Google's DNS servers 8.8.8.8 and 8.8.4.4 or Cloudflare's 1.1.1.1.

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