When a request is handled by Railgun, Cloudflare inserts a header with diagnostic information to track how the protocol is doing. If you want to see these headers, you’ll need to use a browser that supports examining header information.
View Railgun header in browser
Google Chrome: View > Developer > Developer Tools menu. You can also install Cloudflare’s Claire extension.
Safari: Develop > Show Web Inspector menu
Firefox: Install Firebug
Microsoft Internet Explorer: You can use a tool like Fiddler
When you are looking for the header information, you should be seeing Cloudflare headers like the following in the response:
cf-railgun: e95b1c46e0 0.02 0.037872 0030 9878
The CF-Railgun header has up to five codes separated by a space. In order, these codes and their corresponding values from the example of cf-railgun: e95b1c46e0 0.02 0.037872 0030 9878 listed above are:
- Railgun Request ID: e95b1c46e0 (internal process number that allows us to track what connection handled a request )
- Compression Ratio: 0.02 (the size of the response after Railgun’s delta compression expressed as a percentage)
- Origin Processing Time: 0.037872 (that Railgun waits for the origin web server to generate the page)
- Railgun Flags: 0030 (how a request was processed)
- Version Number: 9878 (indicates the version of the Railgun Listener software on the origin server’s network)