Sustained DNS throughput and new connections with GTM after zone record update.

We've been having some strage behavior lately when we update a zone and transfer to the GTM our throughput reaches about 1 megabit and new connections/sec increase to about 100. Normally, we see around 200k in throughput and less than 50 new connections/sec. This strange behavior seems to "fix" itself in a few hours but we have yet determined the cause and the appropriate resolution as it's different every time but it happens almost everyday regardless of zone modifications. We have found that certain things can alleviate the issue but they don't always work such as incrementing a serial number and transferring the zone to the GTM.

 

 

TL;DR. Sporadic increases in DNS throughput and connections per/second have us perplexed.