Also, if a value is flushed from the cache when its value is still positive, the value effectively becomes zero.
(1) Doesn't make sense to flush a value. I think the intention was to say "if an RRSet is flushed..."
(2) nitpick: "when its value is still positive" sounds like maybe it makes assumptions about the way that caches work. It sounds like the TTL is decremented and updated in the cache over time. Something like "...before the end of the TTL interval" may be better.
(3) I'm not quite sure what "effectively becomes zero" means for data that has been flushed. If its flushed its gone or at least not usable again in the future.
In the "TTL" section this appears:
(1) Doesn't make sense to flush a value. I think the intention was to say "if an RRSet is flushed..."
(2) nitpick: "when its value is still positive" sounds like maybe it makes assumptions about the way that caches work. It sounds like the TTL is decremented and updated in the cache over time. Something like "...before the end of the TTL interval" may be better.
(3) I'm not quite sure what "effectively becomes zero" means for data that has been flushed. If its flushed its gone or at least not usable again in the future.