Public NTP time servers have occasionally been that piece of infrastructure.

NTP is used for synchronizing computer clocks, ultimately using highly-accurate time sources such as atomic clocks. The most authoritative public time servers tend to be run by research universities, national labs, and so on.

Multiple home router vendors have sold devices configured to poll university NTP servers vastly excessively; effectively running a denial-of-service attack against public infrastructure. In a few cases, public time servers have closed down because of abuse by misconfigured consumer devices.

https://en.wikipedia.org/wiki/NTP_server_misuse_and_abuse