What is the name of the domain?
What is the issue you’re encountering
Important Information About the Public Suffix List (PSL) and Cloudflare Subdomain Issues
What feature, service or problem is this related to?
Nameservers
What are the steps to reproduce the issue?
Keywords: “Please ensure you are providing the root domain and not any subdomains”, Add a subdomain to Cloudflare account.
I’m writing to address a concerning trend I’ve observed in this community where users are being directed to add their domains to the Mozilla Public Suffix List (PSL) as a solution for Cloudflare subdomain management issues. As one of the community volunteers with the PSL project, I want to provide important context about what the PSL actually is and why this advice can be problematic.
The Public Suffix List is not a Cloudflare-specific tool or workaround for account limitations. It’s a global internet infrastructure resource maintained by Mozilla volunteers that affects how all browsers, applications, and services worldwide handle cookies, certificates, and domain security policies. When you add a domain to the PSL, you’re not just changing how Cloudflare treats your subdomains - you’re changing how the entire internet treats them.
The PSL was designed for a very specific use case: domains that issue subdomains to mutually-untrusting parties who need cookie isolation from each other. Think of services like GitHub Pages (where user1.github.io and user2.github.io represent completely different users who shouldn’t share cookies) or cloud platforms where different customers get subdomains. If you control all the subdomains under your domain and they’re part of the same organization or website, you probably don’t need PSL inclusion.
Adding your domain to the PSL inappropriately can break your website’s functionality in unexpected ways. Cookies that currently work across your subdomains will stop working. Login systems, shopping carts, analytics, and other features that rely on shared cookies between your main domain and subdomains will break. These changes affect all browsers globally, not just your Cloudflare configuration.
The PSL submission process requires extensive documentation, DNS validation, and can take weeks or months to be reviewed by volunteers. Even if approved, changes can take additional months to propagate to all browsers and applications. If you realize you made a mistake and need to remove your domain, rollbacks are extremely difficult and low priority for the volunteer maintainers.
I’ve noticed that some Cloudflare community responses suggest PSL inclusion as a quick fix for Cloudflare’s subdomain limitations on free accounts. This advice is misguided and potentially harmful. The PSL explicitly states that it doesn’t accept entries whose sole purpose is circumventing third-party rate limits or service restrictions. Such requests are typically rejected, and submitting them wastes everyone’s time.
If you’re having issues with subdomain management on Cloudflare, the appropriate solutions include upgrading your account plan, contacting Cloudflare support directly, or finding alternative technical approaches that don’t involve global internet infrastructure changes. The PSL is not a customer service tool for any particular company’s account limitations.
Before anyone considers submitting to the PSL, I strongly encourage reading the project’s guidelines and understanding the global implications. The PSL serves critical security functions across the internet, and inappropriate submissions dilute its effectiveness while creating unnecessary work for volunteers who maintain this important resource.
I hope this information helps community members make informed decisions and provides moderators with context for offering more appropriate guidance to users facing subdomain challenges with their Cloudflare accounts.