Windows API Reference

DNS Overview

This section provides an overview of the Domain Name System (DNS) as it pertains to Windows programming. DNS is a hierarchical and decentralized naming system for computers, services, or any resource connected to the Internet or a private network. It translates human-readable domain names (like www.example.com) into machine-readable IP addresses (like 192.0.2.1).

The Windows operating system provides a robust set of APIs to interact with the DNS infrastructure, allowing applications to perform name resolution, manage DNS records, and configure DNS client settings.

Key Concepts

  • Domain Names: Hierarchical naming structure, e.g., com, example.com, www.example.com.
  • Resource Records (RRs): Data entries in a DNS database, such as A (address), MX (mail exchanger), CNAME (canonical name), and SRV (service location).
  • Name Resolution: The process of translating a domain name into an IP address or other record information.
  • DNS Client: The component on a Windows machine responsible for performing DNS queries.
  • DNS Server: A server that stores DNS records and responds to DNS queries.

Windows DNS APIs

The Windows DNS client API offers functions to:

  • Query DNS records for a given hostname.
  • Perform reverse DNS lookups (IP address to hostname).
  • Retrieve DNS server information.
  • Register or update DNS records (for dynamic DNS).
  • Configure DNS client settings.

Note: Direct manipulation of DNS server records is typically performed by administrative tools or specialized services. The client APIs are primarily for applications that need to resolve names or interact with the DNS system from a client perspective.

Common Use Cases

  • Establishing network connections to servers by hostname.
  • Discovering services within a network using SRV records.
  • Implementing features that rely on domain name resolution.
  • Network diagnostics and troubleshooting.

To get started with programming DNS in Windows, explore the DNS Functions and DNS Data Structures sections for detailed information on available APIs and their usage.

Example Snippet (Conceptual)

Here's a conceptual representation of how you might query a DNS record using a hypothetical DNS API function:


// Hypothetical function call
DNS_STATUS status = DnsQuery_UTF8("www.example.com", DNS_TYPE_A, NULL, NULL, &pResultList);

if (status == ERROR_SUCCESS) {
    // Process the DNS query results (IP addresses)
    // ...
    DnsRecordListFree(pResultList, DnsFreeRecordList);
} else {
    // Handle error
    // ...
}