HTTP has a good solution/proposal for this: the server can include a stale-on-error=someTimeInSeconds header in addition to the TTL and then every cache is allo

HTTP has a good solution/proposal for this: the server can include a stale-on-error=someTimeInSeconds header in addition to the TTL and then every cache is allowed to continue serving stale data for the specified time while the origin is unreachable. Probably a good idea to include such a mechanism in DNS, too. https://tools.ietf.org/html/rfc5861 https://tools.ietf.org/html/rfc5861