Lets try to capture as many metrics as possible that will help us debug `mesos-dns` better.
Just to give an example of the metrics that come to mind:
a) Total number of records for a given TLD, and a given zone.
b) Number of leadership elections.
c) Number of DNS requests.
d) Number of failed DNS lookups.
e) Number of DNS requests for a given zone.
f) Number of DNS requests for upstream TLD.