Which header gives me timing information about requests?


#1

Fastly’s X-Timer header provides information about the journey a content request takes from end to end, including the time it takes to reach the asset Fastly caches and then return to the requestor. Check out our article "Understanding the X-Timer header for a simple breakdown of the header and what each part means.


#2

Does the X-Timer VE number and the time.elapsed/time.end variables measure the time-to-first-byte? Or the time until all the data has been sent & received by the client? Or something else?

If it’s not TTFB, is there a way to get that data?


#3
  • The header X-Timer will give you something along the lines of the following:

    • X-Timer: S1410218655.631229,VS0,VE56
    • time we received request, time.start, time.end
  • time.elapsed: would measure the time the request hits our server and when we deliver the first byte in the response (TTFB)

  • In vcl_log time.elapsed: would show the delta of when the request hit our server to when the response is fully delivered