Synthetic Browser Timings

We setup a synthetic monitor with a single page HTTP call. Did it for all 10 locations (US, Pacific, Australia, etc.).

Question 1:

Where can I find authoritative documentation of how DNS, SSL, payload.timings.total, etc. How are these calculated? Are these monitors doing page caching? We ask since it if very disturbing that the vast number of SSL and DNS times are -1, and if page caching is being done, that would affect the load times. (test was done for 7 days) of data. See Images.