On Thu, Jan 18, 2024 at 12:53:19PM +0100, Jérôme Nicolle <jerome@ceriz.fr> wrote a message of 36 lines which said:
- Low redundancy of old cables (2) - Total service loss when both cables are down because of congestion on satelite backups
A problem which is not often mentioned is that most (all?) "local caches" (CDN, DNS resolvers, etc) do not have an "offline mode" (or "disconnected-from-master mode"). During an outage, they continue to work for some time then break suddenly, in a not-friendly way, serving various error messages instead of old data and/or useful messages. (For instance, the DNS resolver may not be able to serve stale answers.) The time during which they can continue to work when they are disconnected from their master is typically undocumented (except for the DNS), and discovered only when there is a long outage. Making the Internet work better with sometimes-broken connectivity is still an area of research.