diff --git a/management/templates/external-dns.html b/management/templates/external-dns.html
index 0634ec8..4532c3f 100644
--- a/management/templates/external-dns.html
+++ b/management/templates/external-dns.html
@@ -38,7 +38,7 @@
 <p class="alert" role="alert">
 	<span class="glyphicon glyphicon-info-sign"></span>
 	You may encounter zone file errors when attempting to create a TXT record with a long string.
-	<a href="http://tools.ietf.org/html/rfc4408#section-3.1.3">RFC 4408</a> states a TXT record is allowed to contain multiple strings, and this technique can be used to construct records that would exceed the 255-byte maximum length.
+	<a href="https://tools.ietf.org/html/rfc4408#section-3.1.3">RFC 4408</a> states a TXT record is allowed to contain multiple strings, and this technique can be used to construct records that would exceed the 255-byte maximum length.
 	You may need to adopt this technique when adding DomainKeys. Use a tool like <code>named-checkzone</code> to validate your zone file.
 </p>