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.

---

Instructions

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.

 

# 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:
 

# 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.
 

# 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

The above mentioned sample code is provided to you as is with no representations, warranties or conditions of any kind. You may use, modify and distribute it at your own risk. CITRIX DISCLAIMS ALL WARRANTIES WHATSOEVER, EXPRESS, IMPLIED, WRITTEN, ORAL OR STATUTORY, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NONINFRINGEMENT. Without limiting the generality of the foregoing, you acknowledge and agree that (a) the sample code may exhibit errors, design flaws or other problems, possibly resulting in loss of data or damage to property; (b) it may not be possible to make the sample code fully functional; and (c) Citrix may, without notice or liability to you, cease to make available the current version and/or any future versions of the sample code. In no event should the code be used to support ultra-hazardous activities, including but not limited to life support or blasting activities. NEITHER CITRIX NOR ITS AFFILIATES OR AGENTS WILL BE LIABLE, UNDER BREACH OF CONTRACT OR ANY OTHER THEORY OF LIABILITY, FOR ANY DAMAGES WHATSOEVER ARISING FROM USE OF THE SAMPLE CODE, INCLUDING WITHOUT LIMITATION DIRECT, SPECIAL, INCIDENTAL, PUNITIVE, CONSEQUENTIAL OR OTHER DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Although the copyright in the code belongs to Citrix, any distribution of the sample code should include only your own standard copyright attribution, and not that of Citrix. You agree to indemnify and defend Citrix against any and all claims arising from your use, modification or distribution of the sample code.

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.

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