This article contains information about delegating a Microsoft Domain Naming Service (DNS) or a Berkeley Internet Name Domain (BIND) for Global Server Load Balancing on a NetScaler appliance.

Background

When you use a NetScaler appliance for Global Server Load Balancing, the NetScaler appliance responds to the DNS queries for the configured hosts or sub-domains. Depending on the availability and load, the NetScaler appliance responds to the queries for the configured names with the best possible Global Server Load Balancing service IP address.

Instructions

You can access the Microsoft DNS settings from the Administrative Tools sub-menu of the Start menu. Configure the example.com domain by using the DNS tool, as shown in the following screenshot:

Delegating a Microsoft DNS for Global Server Load Balancing on a NetScaler Appliance

To delegate a Microsoft DNS for Global Server Load Balancing on a NetScaler appliance, complete the following procedure:

1. Create the address records for the two NetScaler appliances that you want to handle delegation. These addresses are the Authoritative DNS (ADNS) addresses of each appliance. To create these address, complete the following sub-procedure:

   1. Open the DNS Manager and Right-click the domain.

   2. From the shortcut menu you can also select Net Host (A).

   3. In the Name field, type the NetScaler appliance name.

   4. In the IP address field, type the IP address of the appliance, as shown in the following screen shot:

      

   5. Click Add Host.

   6. Repeat the above procedure to add entries for the other NetScaler appliances as shown above.

2. Remove any entry from the host records, If there is any, for the service we are delegating.

3. Migrate the existing record for subdomain.example.com from an Address record to a delegation. To create a delegation, right-click the domain (example.com) and select New Delegation from the shortcut menu.

4. Click Next in the Delegated Domain Name wizard.

5. Type the sub-domain under 'Delegated domain" you want to delegate.

6. Click Next.

7. Click Add.

8. Select the NetScaler domain name that handles the delegation in the New Resource Record, as shown in the following screenshot:

   

9. Click OK.

10. Repeat Step 7 to Step 9 of this procedure to add the required NetScaler domains, as shown in the following screen shot:

    

11. Click Next.

12. Click Finish.

After completing the preceding procedure, the queries sent to the sub-domain of the DNS server either causes a recursive lookup to the NetScaler appliances or are responded to with the NetScaler records you have configured. To verify this, you can query the DNS server directly for the NetScaler appliance record of the sub-domain, as shown in the following screen shot:

Delegating a BIND for Global Server Load Balancing on a NetScaler Appliance

To delegate a BIND for Global Server Load Balancing on a NetScaler Appliance, complete the following procedure:
Note: In this procedure, it is assumed that you have already created the zone file and appropriately modified the named.conf file for the use. Also when configuring BIND, it is important to note that recursion needs to be ON. Recursion setting for BIND can be found in named.conf. If not, zone will not work and BIND DNS server will not be able to reach out to NetScaler for name resolution.

1. Edit the zone file to add the required Address (A) records for the NetScaler appliances. The following are the sample entries to explain the concept:

   ns-east IN   A    10.100.100.1
   ns-west IN   A    20.200.200.1

2. Remove the existing Address (A) records, other than the ones you added in the preceding step.

3. Create the required NameServer records. The following are the sample NameServer records:

   subdomain   IN   NS   ns-east
   subdomain   IN   NS   ns-west

4. Save and close the file.

5. Test the delegation to verify that the NetScaler appliance ADNS address is being returned.

Note: Depending on the DNS tool you use, the DNS query requests a recursive lookup. As a result, the DNS server, which holds the delegation, follows the delegation and requests an Address record from the NetScaler appliance. Therefore, if you have not yet completed the Global Server Load Balancing ADNS setup, you might observe a timeout. You can verify the appropriate setup of the DNS delegation by ensuring the lookup is set to type NS. 

The following is the format for a sample nslookup:

> set type=ns
> server 10.198.4.52
Default server: 10.198.4.52
Address: 10.198.4.52#53
> subdomain.example.com
Server:         10.198.4.52
Address:        10.198.4.52#53

Non-authoritative answer:
subdomain.example.com   nameserver = ns-east.example.com.
subdomain.example.com   nameserver = ns-west.example.com.

Authoritative answers can be found from:
ns-east.example.com     internet address = 10.100.100.1
ns-west.example.com     internet address = 10.200.200.1