diff --git a/src/docs/markdown/caddyfile/options.md b/src/docs/markdown/caddyfile/options.md
index cab8191..5b18ec8 100644
--- a/src/docs/markdown/caddyfile/options.md
+++ b/src/docs/markdown/caddyfile/options.md
@@ -295,6 +295,7 @@ Skips the attempts to install the local CA's root into the system trust store, a
 ##### `acme_ca`
 Specifies the URL to the ACME CA's directory. It is strongly recommended to set this to Let's Encrypt's [staging endpoint](https://letsencrypt.org/docs/staging-environment/) for testing or development. Default: ZeroSSL and Let's Encrypt's production endpoints.
 
+Note that a globally-configured ACME CA may not apply to all sites; see the [hostname requirements](/docs/automatic-https#hostname-requirements) for using the default ACME issuer(s).
 
 ##### `acme_ca_root`
 Specifies a PEM file that contains a trusted root certificate for ACME CA endpoints, if not in the system trust store.