A method of providing spillover between Global Server Load Balancing (GSLB) virtual servers executing on an intermediary device, the intermediary device deployed between a plurality of clients and a plurality of remote sites, the method comprising: (a) identifying, by an intermediary device providing GSLB, a spillover threshold for a first GSLB virtual server of the intermediary device, the first GSLB virtual server resolving DNS requests to a remote site of a plurality of remote sites; (b) monitoring, by the intermediary device, spillover related statistics of each of a plurality of services at the plurality of remote sites; (c) establishing, by the intermediary device, a first spillover aggregate statistic for the plurality of services; (d) determining, by the intermediary device, that the first spillover aggregate statistic exceeds the spillover threshold for the first GSLB virtual server; and (e) receiving, by the intermediary device, a DNS request and directing the DNS request to a second GSLB virtual server of the intermediary device responsive to the determination; characterised in that: step (a) further comprises identifying a predetermined percentage of healthy services as the spillover threshold; step (c) further comprises establishing as the first spillover aggregate statistic a health for the plurality of services by summing weights of each of the plurality services identified via monitoring as up and dividing the summed weights by a sum of weights of each of the plurality services identified as enabled; and step (d) further comprises determining that the health for the plurality of services exceeds the predetermined percentage of healthy services as the spillover threshold. (a) identifying, by an intermediary device providing GSLB, a spillover threshold for a first GSLB virtual server of the intermediary device, the first GSLB virtual server resolving DNS requests to a remote site of a plurality of remote sites; (b) monitoring, by the intermediary device, spillover related statistics of each of a plurality of services at the plurality of remote sites; (c) establishing, by the intermediary device, a first spillover aggregate statistic for the plurality of services; (d) determining, by the intermediary device, that the first spillover aggregate statistic exceeds the spillover threshold for the first GSLB virtual server; and (e) receiving, by the intermediary device, a DNS request and directing the DNS request to a second GSLB virtual server of the intermediary device responsive to the determination; characterised in that: step (a) further comprises identifying a predetermined percentage of healthy services as the spillover threshold; step (c) further comprises establishing as the first spillover aggregate statistic a health for the plurality of services by summing weights of each of the plurality services identified via monitoring as up and dividing the summed weights by a sum of weights of each of the plurality services identified as enabled; and step (d) further comprises determining that the health for the plurality of services exceeds the predetermined percentage of healthy services as the spillover threshold. step (a) further comprises identifying a predetermined percentage of healthy services as the spillover threshold; step (c) further comprises establishing as the first spillover aggregate statistic a health for the plurality of services by summing weights of each of the plurality services identified via monitoring as up and dividing the summed weights by a sum of weights of each of the plurality services identified as enabled; and step (d) further comprises determining that the health for the plurality of services exceeds the predetermined percentage of healthy services as the spillover threshold.