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+# DynDNS Updater
+
+A dynamic DNS updater service that automatically updates DNS records with your current IP address.
+
+## Configuration (config.json)
+
+The `config.json` file contains all settings for the updater. Here's a detailed explanation of each option:
+
+### Root Level Options
+
+#### `ip_lookup` (required)
+Specifies the services used to discover your public IP addresses.
+
+```json
+"ip_lookup": {
+  "ipv4": ["https://api.ipify.org", "..."],
+  "ipv6": ["https://api6.ipify.org", "..."]
+}
+```
+
+- **`ipv4`** (array of URLs): List of services to query for your IPv4 address. Services are tried in random order until one succeeds.
+- **`ipv6`** (array of URLs): List of services to query for your IPv6 address. Services are tried in random order until one succeeds.
+
+#### `domains` (required)
+Dictionary containing the active domain configurations to update. Each key is a domain name, and each value is a domain configuration object (see below).
+
+```json
+"domains": {
+  "example.com": { ... },
+  "another.com": { ... }
+}
+```
+
+#### `interval` (optional)
+How frequently (in seconds) to check for IP changes and update domains. Defaults to `600` (10 minutes).
+
+```json
+"interval": 300
+```
+
+### Domain Configuration Format
+
+Each entry in the `domains` dictionary has the following structure:
+
+```json
+"example.com": {
+  "modes": ["ipv4", "ipv6"],
+  "url": "https://api.example.com/update",
+  "method": "GET",
+  "params": {
+    "token": "your-token",
+    "domain": "${DOMAIN}",
+    "ip": "${IPV4}"
+  },
+  "headers": {
+    "Authorization": "Bearer token-value"
+  }
+}
+```
+
+#### Domain Options
+
+- **`modes`** (array, optional): Which IP versions to update. Options are `"ipv4"` and/or `"ipv6"`. Defaults to `["ipv4"]`.
+
+- **`url`** (string, required): The endpoint URL of your DNS service provider's update API.
+
+- **`method`** (string, optional): HTTP method to use for the update request. Defaults to `"GET"`. Other options: `"POST"`, `"PUT"`, etc.
+
+- **`params`** (object, optional): Query parameters (for GET/HEAD requests) or request body parameters to send with the update request. Supports variable substitution.
+
+- **`headers`** (object, optional): HTTP headers to include in the request. Supports variable substitution. Use for authentication headers like `Authorization` or `X-API-Key`.
+
+#### Variable Substitution
+
+These variables are automatically replaced in `params` and `headers` values:
+
+- `${DOMAIN}`: The domain name being updated
+- `${IPV4}`: Your current IPv4 address
+- `${IPV6}`: Your current IPv6 address
+
+## Setup
+
+1. Create or edit `config.json` with:
+   - Configure `ip_lookup` with services to detect your public IPs
+   - Add your domain configurations to the `domains` section
+   - Replace placeholder values with your actual API tokens and credentials
+   - Specify which IP versions to update in `modes` for each domain
+   - (Optional) Adjust `interval` if needed
+
+2. Run the updater to start keeping your DNS records current