How to Configure ADNS and DNS Load Balancing on NetScaler Appliance

You can configure a NetScaler appliance to work as an ADNS, where it is authoritative for the domains defined on the appliance and you can also use the NetScaler appliance to load balance external DNS servers.

The following scripts can be used to configure ADNS and DNS load balancing on NetScaler:

NetScaler Appliance Configured as ADNS

You can configure the NetScaler appliance to function as an authoritative DNS for a domain. As an ADNS server for a domain, the NetScaler resolves DNS requests for all types of DNS records that belong to the domain.

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 # NSIP: 10.104.20.180 # MIP: 10.104.20.181 # Note: NetScaler SNIP can also be used for ADNS.  #Create a Name Server:  add dns nameServer 10.104.20.183 -local

Or

 #Create a DNS service:  add service DNS-service 10.104.20.183 ADNS 53  #Create an Address Record: add dns addRec ns1.example.com 10.104.20.183 add dns addRec example.com 10.104.25.16 add dns addRec test.example.com 10.104.19.6 add dns addRec mail.example.com 10.104.20.195 add dns addRec mail1.example.com 10.104.20.196  #Create Name server record:  add dns nsRec example.com ns1.example.com  #Mail Exchanger Records:  add dns mxRec abc.com -mx mail.example.com -pref 1 add dns mxRec abc.com -mx mail1.example.com -pref 2  

Registered ADNS Delegate Sub Domains to NetScaler Appliance

In this scenario, a registered ADNS server exists and you want to delegate only the sub domains to a NetScaler appliance for which the appliance will be acting as an ADNS.

Refer to the following articles for more information:

• Zone delegation in Windows Server
• CTX124727 - How to Configure DNS Delegation Using BIND

Consider that one of the BIND DNS is authoritative for domain example.com and has delegated the subdomain it.example.com to a NetScaler appliance. You need to set up the NetScaler appliance with the following configuration:
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 # NSIP: 10.104.20.180 # MIP: 10.104.20.181 # Note: NetScaler SNIP can also be used for ADNS  #Create a Name Server: add dns nameServer 10.104.20.183 -local

Or

 #Create a DNS service: add service DNS-service 10.104.20.183 ADNS 53  #Add Address Record: add dns addRec ns1.elab.com 10.104.20.183 add dns addRec it.elab.com 10.104.20.190 add dns addRec sales.it.elab.com 10.104.20.191 add dns addRec engg.it.elab.com 10.104.20.192  #Add Name server record: add dns nsRec it.elab.com ns1.elab.com  

Load Balancing External DNS Servers

When you request DNS resolution of a domain name, the NetScaler appliance uses the configured load balancing method to select a DNS service. The DNS server to which the service is bound then resolves the domain name and returns the IP address as the response.
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 # In the proxy mode a DNS service type VIP is created # To this VIP, external DNS servers are bound. # DNS-VIP: 10.104.20.184 # External DNS Servers: 203.124.140.19; 203.124.140.20 # NetScaler appliance will respond to DNS queries on 10.104.20.184 port 53  #Enable Load Balancing Feature: enable ns feature lb  # Add external DNS servers: add service ext_dns_1 203.124.140.19 dns 53 add service ext_dns_2 203.124.140.20 dns 53  # Bind monitor to the service: bind monitor dns ext_dns_1 bind monitor dns ext_dns_2  # Create a DNS virtual server: add lb vserver vdns dns 10.104.20.184 53  #Bind the external DNS services to the DNS virtual server: bind lb vserver vdns ext_dns_1 bind lb vserver vdns ext_dns_2

Citrix Documentation - Load Balancing DNS Servers
Citrix Documentation - Configuring the NetScaler as an ADNS Server

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