The NTP believes further studies of oral preparations of aloe are important, as are studies of the oral exposure of humans to aloe; topical preparations are still considered safe.
When such an implementation finds itself behind a packet filter that refuses to pass the incoming response, this results in a never-ending stream of requests to the NTP server.
This means that for NTP the rollover will be invisible for most running systems, since they will have the correct time to within a very small tolerance.
Since NTP only works with the differences between timestamps and never their absolute values, the wraparound is invisible as long as the timestamps are within 68 years of each other.
To be viable, organisms possess a number of (deoxy) purine phosphohydrolases, which hydrolyze these purine derivatives removing them from the active NTP and dNTP pools.