diff --git a/README.md b/README.md
index 818d5a8..04566ff 100644
--- a/README.md
+++ b/README.md
@@ -22,13 +22,18 @@ The service consists of:
 - **Web Interface**: Bootstrap-based responsive UI
 - **Configuration Parser**: Custom dnsmasq config parser
 - **File Operations**: Safe file reading/writing utilities
+- **Settings Management**: Direct manipulation of dnsmasq configuration files
+  - Updates dnsmasq main configuration (`/etc/dnsmasq.conf`)
+  - Manages hosts file (`/etc/dnsmasq.conf.d/hosts`)
+  - Manages resolv.conf (`/etc/dnsmasq.conf.d/resolv.conf`)
+  - Automatically restarts dnsmasq service after configuration changes
 
 ## API Endpoints
 
 | Method | Endpoint | Description |
 |--------|----------|-------------|
 | GET | `/api/settings` | Get current DNS settings |
-| POST | `/api/settings` | Update DNS settings |
+| POST | `/api/settings` | Update DNS settings (cache_size, resolv servers, hosts) and restart dnsmasq |
 | GET | `/api/settings/file` | Get raw configuration file |
 | POST | `/api/settings/file` | Update configuration file |
 | GET | `/#` | Serve web interface |
@@ -43,6 +48,8 @@ The service consists of:
 ### System Dependencies
 - dnsmasq (for DNS service functionality)
 - SSL certificates (for HTTPS support)
+- System initialization service (systemd, openrc, rc, finit, or init)
+- Appropriate privileges to restart system services
 
 ## Installation
 
@@ -76,7 +83,7 @@ Edit `config.json` to configure the service:
     "tls_enabled": true,
     "tls_cert": "/path/to/certificate.crt",
     "tls_key": "/path/to/private.key",
-    "system_initialization": "rc",
+    "system_initialization": "systemd",
     "dnsmasq_config": "/etc/dnsmasq.conf"
 }
 ```
@@ -89,7 +96,11 @@ Edit `config.json` to configure the service:
 - `tls_enabled`: Enable/disable HTTPS support
 - `tls_cert`: Path to SSL certificate file
 - `tls_key`: Path to SSL private key file
-- `system_initialization`: System initialization type
+- `system_initialization`: System initialization type for restarting dnsmasq service
+  - `"systemd"`: Uses `systemctl restart dnsmasq`
+  - `"rc"` or `"openrc"`: Uses `rc restart dnsmasq`
+  - `"finit"`: Uses `initctl restart dnsmasq`
+  - `"init"`: Uses `/etc/init.d/dnsmasq restart`
 - `dnsmasq_config`: Path to dnsmasq configuration file
 
 ## Usage
@@ -105,11 +116,13 @@ The service will start HTTP server on the configured address (default: `0.0.0.0:
 
 Navigate to `http://localhost:8321` (or your configured address) to access the web interface where you can:
 
-- Configure upstream DNS servers
-- Manage local domain mappings
+- Configure upstream DNS servers (resolv)
+- Manage local domain mappings (hosts)
 - Enable/disable DHCP with range settings
 - Adjust DNS cache size
 - Edit configuration files directly
+- Save settings directly to dnsmasq configuration
+- Automatic dnsmasq service restart after configuration changes
 
 ### API Usage
 
@@ -122,22 +135,63 @@ curl -X GET http://localhost:8321/api/settings
 ```bash
 curl -X POST http://localhost:8321/api/settings \
   -H "Content-Type: application/json" \
-  -d '{"cache_size": 1000, "resolv": ["8.8.8.8", "8.8.4.4"]}'
+  -d '{
+    "cache_size": 1000,
+    "resolv": ["8.8.8.8", "8.8.4.4"],
+    "hosts": {
+      "192.168.1.1": "router.local",
+      "192.168.1.100": ["server1.local", "server1"]
+    }
+  }'
 ```
 
+The POST `/api/settings` endpoint accepts the following parameters:
+- `cache_size` (integer): DNS cache size for dnsmasq
+- `resolv` (array of strings): Upstream DNS servers
+- `hosts` (object): Local DNS mappings where keys are IP addresses and values are either single hostnames (string) or arrays of hostnames
+
+**Note**: After successfully updating the configuration files, the service automatically restarts dnsmasq to apply the changes. The restart method depends on the `system_initialization` setting in `config.json`.
+
+#### Settings Configuration Details
+
+**Cache Size (`cache_size`)**
+- Configures the DNS cache size in dnsmasq
+- Updates the `cache-size` parameter in `/etc/dnsmasq.conf`
+- Accepts integer values (recommended: 150-10000 depending on system resources)
+
+**Upstream DNS Servers (`resolv`)**
+- Array of DNS server IP addresses to use for upstream resolution
+- Creates/updates `/etc/dnsmasq.conf.d/resolv.conf` with `nameserver` entries
+- Example: `["8.8.8.8", "1.1.1.1", "8.8.4.4"]`
+
+**Local Hosts (`hosts`)**
+- Object mapping IP addresses to hostnames for local DNS resolution
+- Creates/updates `/etc/dnsmasq.conf.d/hosts` file
+- Supports both single hostnames and multiple hostnames per IP
+- Format:
+  - Single hostname: `"192.168.1.1": "router.local"`
+  - Multiple hostnames: `"192.168.1.100": ["server1.local", "server1"]`
+
 ## Development
 
 ### Project Structure
 ```
 dns_service_c/
 ├── src/
-│   ├── lib/           # Third-party libraries
-│   │   ├── mongoose.c # HTTP server
-│   │   ├── cJSON.c    # JSON parser
+│   ├── lib/                        # Third-party libraries
+│   │   ├── mongoose.c              # HTTP server
+│   │   ├── cJSON.c                 # JSON parser
 │   │   └── ...
-│   ├── main.c         # Application entry point
-│   ├── config.c       # Configuration management
-│   ├── settings.c     # DNS settings handlers
+│   ├── main.c                      # Application entry point
+│   ├── config.c                    # Configuration management
+│   ├── settings.c                  # DNS settings handlers (GET)
+│   ├── set_settings.c              # DNS settings handlers (POST)
+│   ├── set_dnsmasq_settings_field.c # Update dnsmasq config fields
+│   ├── set_hosts.c                 # Manage hosts file
+│   ├── set_resolvs.c               # Manage resolv.conf
+│   ├── restart_dnsmasq.c           # Restart dnsmasq service
+│   ├── settings.h                  # Settings function declarations
+│   ├── restart_dnsmasq.h           # Restart function declarations
 │   └── ...
 ├── web/               # Web interface files
 │   ├── index.html
@@ -164,10 +218,15 @@ clang-format -i src/*.c src/*.h
 
 ## Security Considerations
 
-- The service runs with system privileges to modify DNS configuration
+- The service runs with system privileges to modify DNS configuration files
 - HTTPS is strongly recommended for production deployments
 - Ensure proper file permissions on certificate files
+- The service directly modifies system files (`/etc/dnsmasq.conf`, `/etc/dnsmasq.conf.d/hosts`, `/etc/dnsmasq.conf.d/resolv.conf`)
 - Consider firewall rules to restrict access to management interface
+- Validate all input data to prevent configuration file corruption
+- Backup configuration files before making changes
+- Ensure the service has appropriate write permissions to dnsmasq configuration directories
+- The service requires privileges to restart the dnsmasq service via system commands
 
 ## Troubleshooting
 
@@ -176,17 +235,34 @@ clang-format -i src/*.c src/*.h
 1. **Permission denied when accessing dnsmasq config**
    - Ensure the service has read/write permissions to the dnsmasq configuration file
    - Run with appropriate privileges or adjust file permissions
+   - Check permissions for `/etc/dnsmasq.conf.d/` directory
 
-2. **SSL/TLS certificate errors**
+3. **Failed to write settings**
+   - Verify write permissions to `/etc/dnsmasq.conf`, `/etc/dnsmasq.conf.d/hosts`, and `/etc/dnsmasq.conf.d/resolv.conf`
+   - Ensure the `/etc/dnsmasq.conf.d/` directory exists
+   - Check disk space availability
+
+4. **Failed to restart dnsmasq**
+   - Ensure the service has appropriate privileges to restart system services
+   - Verify the `system_initialization` parameter in `config.json` matches your system
+   - Supported initialization systems: rc, openrc, systemd, finit, init
+   - Check that dnsmasq service is properly installed and configured on the system
+
+5. **SSL/TLS certificate errors**
    - Verify certificate and key file paths in `config.json`
    - Ensure certificate files have correct permissions
    - Check certificate validity and format
 
-3. **Port binding errors**
+6. **Port binding errors**
    - Verify ports are not already in use
    - Check firewall settings
    - Ensure proper privileges for binding to privileged ports
 
+7. **Settings not persisting after dnsmasq restart**
+   - Ensure dnsmasq is configured to read from `/etc/dnsmasq.conf.d/` directory
+   - Verify the main dnsmasq configuration includes the conf-dir directive
+   - Check that temporary files are properly cleaned up after configuration updates
+
 ### Logging
 The service uses Mongoose's built-in logging. Set log level in code or use debug build for verbose output.
 
diff --git a/src/set_settings.c b/src/set_settings.c
index e2e2549..22c52db 100644
--- a/src/set_settings.c
+++ b/src/set_settings.c
@@ -1,4 +1,5 @@
 #include "settings.h"
+#include "restart_dnsmasq.h"
 
 void set_settings(struct mg_connection *c, struct mg_http_message *hm) {
   cJSON *jsonbody = cJSON_Parse(hm->body.buf);
@@ -57,6 +58,14 @@ void set_settings(struct mg_connection *c, struct mg_http_message *hm) {
     return;
   }
 
+  char *error = restart_dnsmasq();
+  if (error) {
+    mg_http_reply(c, 500, HTTP_HEADERS, "{%m:%m}", MG_ESC("error"),
+                  MG_ESC(error));
+    free(error);
+    return;
+  }
+
   mg_http_reply(c, 200, HTTP_HEADERS, "%s", hm->body.buf);
   cJSON_Delete(jsonbody);
 }