In a typical Global Server Load Balancing (GSLB) deployment, the NetScaler appliance receives DNS queries for A/AAAA records, selects the most appropriate GSLB service according to the configured load balancing method, and returns the service's IP address as a reply to the DNS query. You can now configure the appliance to receive DNS queries for NAPTR records and respond with the list of services configured for a domain. The appliance also monitors the health of the services, and in the response it provides a list of only the services that are up.
In Telco deployments, you can configure a NetScaler appliance to receive DNS queries with NAPTR records from clients such as mobile management entities (MMEs), which play the role of a DNS resolver to discover all the services that are offered by the domain name. The appliance responds to the query with NAPTR records for all the services that are up. The MME can use this NAPTR response to run the S-NAPTR procedure to select the nodes on the basis of the service offered, colocation, topological closeness, and so on.
If multiple nodes qualify for selection, the MME can use the preference field in the NAPTR record from the NetScaler appliance to determine the node.
While responding to a DNS query with NAPTR record, a NetScaler appliance constructs a response NAPTR record for each GSLB service.
The following table lists the files in the NAPTR record:
For detailed GSLB configuration instructions, see Configuring Global Server Load Balancing (GSLB). Make sure that you do the following:
- Set the following parameters while adding the GSLB virtual server:
- serviceType: ANY
- dnsRecordType: NAPTR
- lbMethod: CUSTOMLOAD
add gslb vserver gslb_vs ANY -dnsRecordType NAPTR -lbMethod CUSTOMLOAD
- While adding a GSLB site, set the naptrReplacementSuffix parameter to the domain name that you want to embed in the NAPTR records.
add gslb site site1 10.102.218.200 -naptrReplacementSuffix example.com
- Set the following parameters while adding the GSLB service: