[oasisbob]

In us-east-1? That doesn't sound that impactful, have always heard that us-east-1's network is a ring.

Back before AWS provided transparency into AZ assignments, it was pretty common to use latency measurements to try and infer relative locality and mappings of AZs available to an account.

[Sparkyte]

It was a long time ago. It was very impactful at the time. You could still reach the other AZes but that one. I think this was US-East1c.