For example, GET https://cloudflare.com/cdn-cgi/trace returns
fl=202f30
h=cloudflare.com
ip=<the ip>
ts=<timestamp>
visit_scheme=https
uag=<user agent>
colo=<iata>
http=http/2
loc=<country code>
tls=TLSv1.3
sni=plaintext
warp=off
Most of the fields are self-explanatory, but what does 202f30 represent?
Thanks,
- John
2020-03-19 update: “FL accepts plain HTTP connections and does the main request logic, including our WAF” from Keepalives considered harmful
fl references our webserver and (I suspect) the value applies to a particular instance.
Webservers are tied to a colo? This field appears to always differ per colo for the same hosted domain, but has some client affinity within a colo, subsequent requests have the same value for a while. What is the abbreviation fl short for?
Also, what does an instance refer to in this context? The hosted domain?
I receive sometimes different values in the same colo, so I don’t think they’re tied 1 to 1. Instance referenced an instance of the server, not of a domain. I’ll look to see if I can find any details describing but I associate fl with flare.
By “tied to a colo” I mean “exist within a single colo” (many to 1), i.e. I never see the same flare in different colos. At least I haven’t yet…
Would love to see some official documentation on how this value ties to the underlying infrastructure.
Just curious!
Will share what I find. Chatted with the team, the fl designation is ultimately meaningless, was from an old team designation. The value identifies an instance.
This topic was automatically closed after 14 days. New replies are no longer allowed.