DnsClinet.NET
DnsClient.NET is a simple yet very powerful open source library
...It provides a simple API for running DNS queries while still exposing advanced configuration options. The library supports both synchronous and asynchronous usage, making it suitable for command-line tools, services, and application backends. It can perform UDP and TCP lookups, with configurable TCP fallback when UDP responses are truncated. It also includes caching based on DNS TTL values, which helps reduce repeated lookups in high-traffic scenarios. With support for many DNS record types, it gives developers a flexible foundation for DNS resolution and diagnostics.