diff --git a/nixos/boxes/colony/default.nix b/nixos/boxes/colony/default.nix
index 4ab1ab5..a839cb8 100644
--- a/nixos/boxes/colony/default.nix
+++ b/nixos/boxes/colony/default.nix
@@ -9,6 +9,7 @@
     assignments = {
       internal = {
         altNames = [ "vm" ];
+        domain = lib.my.colony.domain;
         ipv4.address = "${lib.my.colony.start.base.v4}2";
         ipv6 = {
           iid = "::2";
@@ -32,8 +33,6 @@
       {
         imports = [ "${modulesPath}/profiles/qemu-guest.nix" ];
 
-        networking.domain = lib.my.colony.domain;
-
         boot.kernelParams = [ "intel_iommu=on" ];
         boot.loader.systemd-boot.configurationLimit = 20;
         fileSystems = {
diff --git a/nixos/boxes/colony/vms/estuary/default.nix b/nixos/boxes/colony/vms/estuary/default.nix
index 8168dcd..4ae25f9 100644
--- a/nixos/boxes/colony/vms/estuary/default.nix
+++ b/nixos/boxes/colony/vms/estuary/default.nix
@@ -8,6 +8,7 @@
       internal = {
         name = "estuary-vm";
         altNames = [ "fw" ];
+        domain = lib.my.colony.domain;
         ipv4 = {
           address = "80.111.124.10";
           gateway = null;
@@ -37,8 +38,6 @@
 
         config = mkMerge [
           {
-            networking.domain = lib.my.colony.domain;
-
             boot.kernelParams = [ "console=ttyS0,115200n8" ];
             fileSystems = {
               "/boot" = {
diff --git a/nixos/boxes/colony/vms/shill/containers/middleman.nix b/nixos/boxes/colony/vms/shill/containers/middleman.nix
index f3b281d..f5de0a9 100644
--- a/nixos/boxes/colony/vms/shill/containers/middleman.nix
+++ b/nixos/boxes/colony/vms/shill/containers/middleman.nix
@@ -7,6 +7,7 @@
       internal = {
         name = "middleman-ctr";
         altNames = [ "http" ];
+        domain = lib.my.colony.domain;
         ipv4.address = "${lib.my.colony.start.ctrs.v4}2";
         ipv6 = {
           iid = "::2";
diff --git a/nixos/boxes/colony/vms/shill/containers/vaultwarden.nix b/nixos/boxes/colony/vms/shill/containers/vaultwarden.nix
index ebaa32f..7cd34f1 100644
--- a/nixos/boxes/colony/vms/shill/containers/vaultwarden.nix
+++ b/nixos/boxes/colony/vms/shill/containers/vaultwarden.nix
@@ -6,6 +6,7 @@
     assignments = {
       internal = {
         name = "vaultwarden-ctr";
+        domain = lib.my.colony.domain;
         ipv4.address = "${lib.my.colony.start.ctrs.v4}3";
         ipv6 = {
           iid = "::3";
diff --git a/nixos/boxes/colony/vms/shill/default.nix b/nixos/boxes/colony/vms/shill/default.nix
index 63cf955..373dfa5 100644
--- a/nixos/boxes/colony/vms/shill/default.nix
+++ b/nixos/boxes/colony/vms/shill/default.nix
@@ -9,6 +9,7 @@
       internal = {
         name = "shill-vm";
         altNames = [ "ctr" ];
+        domain = lib.my.colony.domain;
         ipv4.address = "${lib.my.colony.start.vms.v4}2";
         ipv6 = {
           iid = "::2";
@@ -35,8 +36,6 @@
 
         config = mkMerge [
           {
-            networking.domain = lib.my.colony.domain;
-
             boot.kernelParams = [ "console=ttyS0,115200n8" ];
             fileSystems = {
               "/boot" = {
diff --git a/nixos/default.nix b/nixos/default.nix
index 53b3c96..2cdaa78 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -1,8 +1,8 @@
 { lib, pkgsFlakes, hmFlakes, inputs, pkgs', config, ... }:
 let
   inherit (builtins) attrValues mapAttrs;
-  inherit (lib) substring flatten optional optionals mkDefault mkForce mkOption mkOptionType;
-  inherit (lib.my) naiveIPv4Gateway homeStateVersion mkOpt' mkBoolOpt' commonOpts inlineModule';
+  inherit (lib) substring flatten optional optionals mkIf mkDefault mkForce mkOption mkOptionType;
+  inherit (lib.my) naiveIPv4Gateway homeStateVersion mkOpt' mkBoolOpt' mkDefault' commonOpts inlineModule';
 
   cfg = config.nixos;
 
@@ -50,7 +50,10 @@ let
           };
 
           system.name = name;
-          networking.hostName = mkDefault (config'.assignments.internal.name or name);
+          networking = {
+            domain = let d = config'.assignments.internal.domain; in mkIf (d != null) (mkDefault' d);
+            hostName = mkDefault (config'.assignments.internal.name or name);
+          };
           nixpkgs = {
             inherit (config') system;
             # Make sure any previously set overlays (e.g. lib which will be inherited by home-manager down the
@@ -94,6 +97,7 @@ let
       name = mkOpt' str name "Name of assignment.";
       altNames = mkOpt' (listOf str) [ ] "Extra names to assign.";
       visible = mkBoolOpt' true "Whether or not this assignment should be visible.";
+      domain = mkOpt' (nullOr str) null "Domain for this assignment.";
       ipv4 = {
         address = mkOpt' str null "IPv4 address.";
         mask = mkOpt' ints.u8 24 "Network mask.";