Defines BaseProvider and SimpleProvider abstract classes that standardize the interface for DNS providers. This plugin system allows adding new providers without modifying core logic, demonstrating isolation and reusability. Each provider implements methods like query_record, create_record, and update_record, enabling the core update loop to work uniformly across different DNS services.

Handles loading configuration from multiple sources (CLI arguments, JSON files, environment variables) with a defined precedence (CLI > JSON > ENV). It supports JSON with comments (stripping # and // comments) and applies defaults and validation. This isolated component is reusable in any application needing flexible configuration and demonstrates skill in managing complex configuration sources without tight coupling.

Provides a robust HTTP client with automatic retry (exponential backoff), proxy support (HTTP, HTTPS, SOCKS), SSL configuration, and timeout handling. Used throughout the application for IP detection and DNS provider API calls, this utility is self-contained and extractable for projects requiring reliable HTTP requests. It demonstrates non-obvious skill in handling edge cases like SSL context management and proxy type negotiation.