lib/dns: fix reverseZones4 to be complete

nix/lib/dns.nix

@@ -10,6 +10,7 @@ rec {
   publicNS = [ "ns.c3d2.de" "ns.spaceboyz.net" ];
   
   dynamicReverseZones = [
+    "73.20.172.in-addr.arpa"
     "74.20.172.in-addr.arpa"
     "75.20.172.in-addr.arpa"
     "76.20.172.in-addr.arpa"
@@ -64,16 +65,18 @@ rec {
       ) {} (builtins.attrValues namedNets);
 
       # `[ "0.0.127.in-addr.arpa" ]`
-      reverseZones4 = builtins.attrNames (
-        builtins.foldl' (result: rname:
-          let
-            zone = builtins.head (
-              builtins.match "[[:digit:]]+\\.(.+)" rname
-            );
-          in result // {
-            "${zone}" = true;
-          }
-        ) {} (builtins.attrNames reverseHosts4)
+      reverseZones4 = lib.unique (
+        builtins.attrNames (
+          builtins.foldl' (result: rname:
+            let
+              zone = builtins.head (
+                builtins.match "[[:digit:]]+\\.(.+)" rname
+              );
+            in result // {
+              "${zone}" = true;
+            }
+          ) {} (builtins.attrNames reverseHosts4)
+        ) ++ dynamicReverseZones
       );
 
       # turns `::` into `0000:0000:0000:0000:0000:0000:0000:0000`