diff --git a/README.md b/README.md
index 92104af..40c69ee 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ and pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_867 TILs and counting..._
+_868 TILs and counting..._
 
 ---
 
@@ -117,6 +117,7 @@ _867 TILs and counting..._
 - [Reload The nginx Configuration](devops/reload-the-nginx-configuration.md)
 - [Resolve The Public IP Of A URL](devops/resolve-the-public-ip-of-a-url.md)
 - [Running Out Of inode Space](devops/running-out-of-inode-space.md)
+- [SSL Certificates Can Cover Multiple Domains](devops/ssl-certificates-can-cover-multiple-domains.md)
 - [Wipe A Heroku Postgres Database](devops/wipe-a-heroku-postgres-database.md)
 
 ### Elixir
diff --git a/devops/ssl-certificates-can-cover-multiple-domains.md b/devops/ssl-certificates-can-cover-multiple-domains.md
new file mode 100644
index 0000000..5d8caa7
--- /dev/null
+++ b/devops/ssl-certificates-can-cover-multiple-domains.md
@@ -0,0 +1,10 @@
+# SSL Certificates Can Cover Multiple Domains
+
+When registering an SSL certificate, you can list multiple domains to be
+covered by it.
+
+One use case is registering a certificate that covers both the apex domain
+(`example.com`) and all subdomains using a wildcard (`*.example.com`). The
+wildcard alone will not cover `example.com`. If you want `example.com`,
+`www.example.com`, `blog.example.com`, etc. covered under the same certificate,
+then you'll need to include both the apex and wildcard domains.