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Instructions

 
    This can be achieved on NetScaler using Content Switching Policy with "DNS.REQ" Expression.

    Add both the DNS Server's to LB Servers with Services.

   
   
   

   Create 2 LB VIP's 1 for each server.

  

   Create Content Switching Policies for both the domain's.

  

   Create Content Switching Vserver for DNS Type Traffic.

  

   Bind both CS Policies created to this CS Vserver along with their Target Load Balancing Virtual Server.

  


   To Verify Operations for this config, Please look at the screenshot attached from a packet capture collected on NetScaler.
   Client IP: - 10.104.61.131
   VIP: - 10.104.61.141
   SNIP: - 10.104.61.133
   DSTIP: - 10.104.61.135/136

 



  Note:- All the ip addresses and Domain's used in this Article are internal only.
  You can even configure LB Vserver to have non-addressable address like 0.0.0.0 and use them within CS Vserver for Target Load Balancing VServer.
 

If you've multiple DNS Servers as a part of different domain's , we can configured NS to send queries for each domain to their respective DNS Servers