Load Balancing DNS requests with NLB

Bojan Zivkovic 436 Reputation points
2024-04-25T10:37:47.1433333+00:00

Hi, I want to clear this up - is it possible/recommended to load balance DNS requests with Network Load Balancing feature of Windows Server (inbound tcp/53 and udp/53)? DNS servers are also DCs of course. Preferred DNS Server in tcp/ip settings on servers would be an IP of NLB Cluster. Something tells me this is not a good idea so feedback would be highly appreciated.

Windows Server
Windows Server
A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.
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  1. Yanhong Liu 2,950 Reputation points Microsoft Vendor
    2024-04-29T07:19:23.01+00:00

    Hello,

    It is possible to load balance DNS requests using Windows Server's Network Load Balancing (NLB) feature, but this is not a recommended practice, especially when the DNS server is also a domain controller (DC). Here’s why:

    1. Stability and consistency of domain controller: Domain controller is a key component in the domain and is responsible for authentication and authorization services. If a DNS server is configured in NLB, it may cause stability and consistency issues on the domain controller, affecting the overall health of the domain.
    2. Consistency of DNS resolution: In a domain environment, the consistency of DNS resolution is very important. Using NLB for load balancing may cause inconsistencies in DNS queries, affecting the normal operation of clients and the stability of domain services.
    3. Suggested alternatives: In order to achieve high availability and load balancing of DNS services, you can consider using specialized DNS resolution load balancing equipment or software or deploy multiple independent DNS servers and use other load balancing technologies (such as Round Robin DNS) to distribute traffic.

    In summary, although it is possible to use NLB to load balance DNS requests, it is not recommended to implement this configuration on domain controllers to ensure the stability and consistency of domain services.

    I hope the above information is helpful to you.

    Sincerely,

    Liu Yanhong

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