Global Server Load Balancing (GSLB) Persistence, also known as ‘Stickiness’, is the property that enables all name resolution requests from an individual client to be sent to the same set of resources until a specified period of time (in seconds) has elapsed. This ensures that users are able to retrieve and interact with session-specific data. Stickiness can be set globally in the Miscellaneous Params section, or for an individual FQDN.

If connecting from a client to the GEO LoadMaster directly, the GEO LoadMaster keeps a persistence entry for the request. If connecting from a DNS server to the GEO LoadMaster directly, the GEO will keep a persistence entry for the request, as will the DNS server. When troubleshooting, ensure to set Stickiness to 0 and clear the DNS cache on the DNS server (Dnscmd /clearcache on Windows Server).

If EDNS Client Subnet (ECS) option (in Global Balancing > Miscellaneous Params) is enabled, the GEO LoadMaster uses the ECS value instead (if one is received) for direct connection to the client or DNS server. If disabled, the GEO LoadMaster uses the client or DNS server request’s source IP address for direct connection.

Note: It is possible that a client that has EDNS enabled may be sending requests through recursive DNS servers that are not enabled for EDNS. That means the client subnet will be dropped from the UDP packet that is received by the LoadMaster. If the EDNS client subnet information is removed it will not be available for the LoadMaster to act on.

For further information, refer to the GEO Sticky DNS, Feature Description.