Unlike traditional DNS servers that simply respond with the IP addresses of the configured servers, a NetScaler appliance configured for GSLB responds with the IP addresses of the services, as determined by the configured GSLB method. By default, the GSLB virtual server is set to the least connection method. If all GSLB services are down, the NetScaler responds with the IP addresses of all the configured GSLB services.
GSLB methods are algorithms that the GSLB virtual server uses to select the best-performing GSLB service. After the host name in the Web address is resolved, the client sends traffic directly to the resolved service IP address.
The NetScaler appliance provides the following GSLB methods:
- Round Robin
- Least Connections
- Least Response Time
- Least Bandwidth
- Least Packets
- Source IP Hash
- Custom Load
- Round Trip Time (RTT)
- Static Proximity
For GSLB methods to work with a remote site, either MEP must be enabled or explicit monitors must be bound to the remote services. If MEP is disabled, RTT, Least Connections, Least Bandwidth, Least Packets and Least Response Time methods default to Round Robin.
The Static Proximity and RTT load balancing methods are specific to GSLB.