diff --git a/functions/network.xml b/functions/network.xml
index 081aadddd7..bb0ecd7797 100644
--- a/functions/network.xml
+++ b/functions/network.xml
@@ -35,6 +35,9 @@
      <parameter>Host</parameter> may either be the IP address in
      dotted-quad notation or the host name.
     </simpara>
+    <simpara>
+     <function>checkdnsrr</function> is not available on windows.
+    </simpara>
     <simpara>
      See also <function>getmxrr</function>,
      <function>gethostbyaddr</function>,