For high availability, it is recommended to configure DNS for GSLB on a Service Engine (SE) group that is scalable to two or more SEs. It is also recommended to implement DNS for GSLB in more than one location.
This can be implemented in the following ways:
Have at least two geographically separated active GSLB sites. For each site configure DNS onto a scalable SE group.
If only one active site is defined, ensure a minimum of at least one geographically remote cloud. On that remote cloud, configure DNS for GSLB on a scalable SE group. Also define all virtual services to support the mission-critical applications running on the origin location.