Test from San Jose Location.


I ran a test from San Jose, CA location

We have a CDN for serving our static content. Looking at the IP from where were the requests are being served, they all come from either East Coast or Mid west. When we contacted them, they said that they serve the content based on ISP’s DNS IP address.

Can you let us know the IP of the ISP’s DNS server for San Jose Location. Also can you provide us the IP range of the San Jose machines that is being used for the test.


You can get IP addresses for all of the agents here: http://www.webpagetest.org/getTesters.php

That said, your CDN probably meant to say that they serve content based on the IP address of the ISP’s DNS server.

I don’t have direct access to those for all of the locations but it’s usually fairly easy to see by running a tcpdump with the test and just watching to see where the DNS requests are sent. I say “usually” because for some reason the tcpdumps are not working from San Jose :-/

In the case of San Jose I do have access though so I pulled the list of DNS servers:
Primary -
Secondary -

As DNS is usually anycast you need to run a traceroute from the test agent to figure out where it goes: http://www.webpagetest.org/result/120831_GX_CKB/

Being ~1ms away from the test server pretty much guarantees that the DNS servers are on the west coast (probably in the same data center).