Configuring DNS over HTTPS (DoH) on Windows Server 2019: A Comprehensive Guide

DNS over HTTPS (DoH) enhances the privacy and security of your DNS lookups by encrypting them over HTTPS. While Windows Server 2019 doesn't natively support DoH for all clients, you can configure it for specific applications or users using various methods. This guide explores several approaches, detailing their pros and cons and offering step-by-step instructions.

Understanding the Limitations of Native Support

Unlike client operating systems like Windows 10 and 11, which offer built-in DoH support through settings, Windows Server 2019 lacks a direct, built-in mechanism. This means you can't simply enable DoH globally for all network clients. Instead, you'll need to implement workarounds involving either modifying client configurations or using a proxy server.

Method 1: Client-Side Configuration (Recommended for Limited Deployments)

This method involves directly configuring the DoH settings within applications or on individual client machines. This approach is ideal for a small number of devices or specific applications where you want to enforce DoH.

Steps:

• Identify your preferred DoH provider: Popular options include Cloudflare (https://cloudflare-dns.com/dns-query), Google Public DNS (https://dns.google/dns-query), and Quad9 (https://dns.quad9.net/dns-query). Choose one based on your privacy preferences and performance requirements.
• Modify client applications: Some applications allow you to specify custom DNS servers. Look for DNS settings within the application's configuration.
• Configure the DNS settings on individual clients: This is usually done through the network adapter settings. The process involves setting a custom DNS server address. However, this will likely require manual intervention on each client, and will not use DoH without additional software.

Pros: Simple to implement for a small number of clients, direct control over DoH usage per application or client.

Cons: Requires manual configuration for each client, not scalable for large deployments.

Method 2: Using a Proxy Server (Recommended for Large Deployments)

A proxy server acts as an intermediary between your clients and the DoH provider. The clients connect to the proxy, and the proxy handles the encrypted DoH requests. This offers central management and improved scalability.

Steps:

• Choose a suitable proxy server: You can use a dedicated proxy server or even leverage existing servers within your network. Consider servers capable of handling DNS requests and supporting HTTPS.
• Configure the proxy server for DoH: This typically involves setting up a reverse proxy or using specialized DNS-over-HTTPS proxy software. The exact configuration will depend on the chosen proxy server and software.
• Configure clients to use the proxy: This involves directing clients to use the proxy server for internet access, including DNS lookups. This is done through the network settings of individual clients or by configuring group policies.

Pros: Centralized management, scalability for large deployments, improved security and manageability.

Cons: More complex to set up and maintain, requires additional server infrastructure.

Method 3: Third-Party DNS Solutions

Several third-party DNS solutions offer built-in support for DoH. These solutions often come with advanced features like caching and security enhancements. Deploying such a solution will greatly simplify the process and reduce management overhead compared to manual server configurations. However, this typically involves a subscription fee or licensing cost.

Security Considerations

While DoH enhances privacy, remember to choose a reputable DoH provider with a strong security track record. Also, carefully configure and secure your proxy server if using that method to prevent unauthorized access or tampering.

Conclusion

Implementing DoH on Windows Server 2019 requires a pragmatic approach based on your environment's specific needs and scale. While native support is lacking, client-side configuration, using a proxy server, or adopting third-party DNS solutions provide viable and secure alternatives. Careful planning and consideration of security aspects are crucial to ensure a successful and secure DoH deployment.