Created a central place for all common options to all hosts.

modules/machine-types/common.nix

@@ -0,0 +1,60 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.environment;
+in {
+  options.environment = {
+    ntpServers = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "0.pool.ntp.org" "1.pool.ntp.org" ];
+      description = "NTP servers for this environment.";
+    };
+
+    dnsServers = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "1.1.1.1" "8.8.8.8" ];
+      description = "Authoritative DNS servers for this environment.";
+    };
+
+    domain = mkOption {
+      type = types.str;
+      default = "";
+      example = "example.org";
+      description = "DNS domain for this environment.";
+    };
+
+    timeZone = mkOption {
+      type = types.str;
+      default = "UTC";
+      example = "Europe/Paris";
+      description = "Timezone for this environment.";
+    };
+
+    hardwareClock = mkOption {
+      type = types.str;
+      default = "UTC";
+      example = "UTC";
+      description = "Hardware clock setting for this environment.";
+    };
+  };
+
+  config = {
+    # System state version — defined once here for all machine types
+    system.stateVersion = "25.11";
+
+    # NTP servers
+    services.ntp.servers = cfg.ntpServers;
+
+    # Time settings
+    time.timeZone = cfg.timeZone;
+    time.hardwareClock = cfg.hardwareClock;
+
+    # Domain and DNS servers
+    networking.domain = cfg.domain;
+    networking.nameServers = cfg.dnsServers;
+  };
+}

modules/machine-types/hypervisor/default.nix

@@ -1,4 +1,6 @@
 { config, pkgs, lib, ... }:
 {
+  imports = [ ./../common ];
+
   # TODO: Add hypervisor-specific configuration
-}
+}

modules/machine-types/lxc/default.nix

@@ -1,6 +1,9 @@
 { config, modulesPath, pkgs, lib, ... }:
 {
-  imports = [ (modulesPath + "/virtualisation/proxmox-lxc.nix") ];
+  imports = [
+    ./../common
+    (modulesPath + "/virtualisation/proxmox-lxc.nix")
+  ];
   nix.settings = { sandbox = false; };  
   proxmoxLXC = {
     manageNetwork = false;
@@ -43,6 +46,4 @@
 
   };
 
-  system.stateVersion = "25.11";
-
-}
+}

modules/machine-types/vm/default.nix

@@ -1,4 +1,6 @@
 { config, pkgs, lib, ... }:
 {
+  imports = [ ./../common ];
+
   # TODO: Add VM-specific configuration
-}
+}

modules/machine-types/workstation/default.nix

@@ -1,4 +1,6 @@
 { config, pkgs, lib, ... }:
 {
+  imports = [ ./../common ];
+
   # TODO: Add workstation-specific configuration
-}
+}