diff --git a/dns/types/simple.nix b/dns/types/simple.nix
index 3e089a8..e15cc3a 100644
--- a/dns/types/simple.nix
+++ b/dns/types/simple.nix
@@ -7,9 +7,21 @@
 let
   inherit (builtins) stringLength;
 
+  # RFC 1035, 3.1
+  domain-name = lib.types.addCheck lib.types.nonEmptyStr (s: stringLength s <= 255) // {
+    description = "an RFC 1035 DNS domain name";
+  };
 in
 
 {
-  # RFC 1035, 3.1
-  domain-name = lib.types.addCheck lib.types.str (s: stringLength s <= 255);
+  inherit domain-name;
+
+  # RFC 2181, section 11
+  domain-label = lib.types.addCheck lib.types.nonEmptyStr (s: stringLength s <= 63) // {
+    description = "a DNS label";
+  };
+
+  fqdn = lib.types.addCheck domain-name (lib.strings.hasSuffix ".") // {
+    description = "a fully-qualified DNS domain name";
+  };
 }