How does split-horizon DNS work in hybrid on-prem and cloud networks?

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How does split-horizon DNS work in hybrid on-prem and cloud networks?

Asked on Nov 18, 2025

Answer

Split-horizon DNS, also known as split-view or split-brain DNS, is a method used to provide different DNS responses based on the origin of the DNS query, which is particularly useful in hybrid on-premises and cloud networks. This approach allows organizations to manage internal and external DNS records separately, ensuring that internal users and systems receive internal IP addresses, while external users are directed to public-facing IP addresses.

Example Concept: In a split-horizon DNS setup, an organization configures its DNS servers to provide different IP address resolutions based on whether the DNS query originates from within the internal network or from an external source. For instance, an internal query for "app.example.com" might resolve to a private IP address within the organization's VPC, while an external query for the same domain resolves to a public IP address. This setup is crucial in hybrid environments to ensure seamless access to resources while maintaining security and optimizing traffic routing.

Additional Comment:

Split-horizon DNS can be implemented using DNS servers like BIND, Microsoft DNS, or cloud-based DNS services that support policy-based responses.
Proper configuration ensures that internal resources are not exposed to the public internet, enhancing security.
It's essential to maintain consistent DNS records and policies to prevent resolution conflicts or access issues.
Monitoring and logging DNS queries can help identify misconfigurations or unauthorized access attempts.

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