I built this little toy last week in just a few lines of code. Its only job is to turn short links into absurdly long ones, taking full advantage of the maximum 63-character limit for a single DNS label:
loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.ong
While the application logic was trivial, getting it deployed ran straight into a weird TLS edge case: certificate issuance.
- The maximum length of a single DNS domain label is 63 characters.
- In traditional X.509 TLS certificates, the
commonName(CN) field has a strict limit of 64 characters. - Because
loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.ongis 67 characters total (63 + 1 + 3), putting the full domain into thecommonNamefails validation.
This caused automated Let’s Encrypt issuance to fail across Cloudflare, Vercel, and Netlify, because their ACME pipelines put the domain into the commonName field. Interestingly, Zeabur managed to issue a Let’s Encrypt certificate, likely because their ACME client left the CN empty and relied exclusively on the Subject Alternative Name (SAN) extension.
On Cloudflare, I resolved it by switching the edge certificate authority from Let’s Encrypt to Google Trust Services (GTS), which issued the certificate immediately.
You can view the certificate details on crt.sh: https://crt.sh/?q=loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.ong
Live site: https://loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.ong