Global Server Load Balancer

Description

Global Server Load Balancing (called GSLB) is a feature that enables load balancing across data centres.

GSLB is typically used to provide data centre fail-over or to enhance end user performance by directing users to their closest data centres using geolocation.

GSLB is a DNS based system that manipulates the DNS response based on the availability and performance profile of the data centres.

How does GSLB work?

The preferred configuration is to use the high performance DNS server on the Edgenexus ADC and make it authoritative for a subdomain, such as www.gslb.com

All DNS requests will be sent to the root server, for example gslb.com.

The root server will know that there is a server that is authoritative for that particular subdomain and consequently, the request will be sent to Edgenexus GSLB for resolution.

The Edgenexus ADC continually monitors the health of the data centres and can apply custom application level health checks.

Depending on the GSLB mode selected, the ADC will answer the DNS request with the External IP of the service at the appropriate data centre.

The response can depend on a number of factors including:

• The load on the data centres
• The availability of the data centres
• Information fed back from the health checks
• The client’s physical location