Re: Cloudflare blocking Cogent again

[David Hubbard via NANOG <nanog () lists nanog org>]

Are you sure it’s not the Cloudflare customers choosing to block the Cogent ASN?  i.e. are you seeing a CF blocking 
message rather than just a transit failure?

Reason I ask is because we see a reasonable number of bot attacks sourced from AS174 end customers, so I could see 
sites like the ones you mentioned choosing to block rather than challenge.  Cloudflare’s challenges seem to be getting 
bypassed by bots more and more lately, and their support doesn’t seem to care, so some users may resort to blocking.

From: Miller, Jon via NANOG <nanog () lists nanog org>
Date: Monday, August 11, 2025 at 2:01 PM
To: nanog () lists nanog org <nanog () lists nanog org>
Cc: Miller, Jon <JMiller () boselaw com>
Subject: Cloudflare blocking Cogent again
We are seeing multiple Cloudflare sites blocked on our Cogent circuits.  Three Cogent circuits from two clients in two 
states are blocked.  I opened a ticket with Cogent, but the last time this happened, they just shrugged and said "not 
our fault."  Are any other Cogent customers seeing this?  Any advice on how to resolve?  Here are the sites we see 
blocked by Cloudflare.

https://www.americanbar.org/
https://www.ballys.com/
https://investor.fanatics.com/investor-relations/default.aspx


Jon Miller
Bose McKinney & Evans LLP

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