persistence, when a DNS request is received at a data center, the NetScaler
appliance first looks for an entry in the persistence table and, if an entry
for the local DNS server exists and the server mentioned in the entry is
configured, the IP address of that server is sent as the DNS response.
For the first
request from a particular client, the NetScaler appliance selects the best GSLB
site for the request and sends its IP address to the client. Since persistence
is configured for the source IP address of the client, all subsequent requests
by that client or another local DNS server in the same IP subnet are sent the
IP address of the GSLB site that was selected for the first request.
address based persistence, the same set of persistence identifiers must be
configured on the GSLB virtual servers in all data centers. A persistence
identifier is a number used by the data centers to identify a particular GSLB
virtual server. A cookie transmits the persistence identifier, enabling the
NetScaler appliance to identify the domain so that it can forward all
appropriate requests to the same domain. When persistence is enabled, the
persistence information is also exchanged as part of metrics exchange.
For the NetScaler
appliance to support persistence across sites, persistence must be enabled on
the GSLB virtual servers of all participating sites. When you use source IP
address persistence on the network identifier, you must configure a subnet
mask. For any domain, persistence takes precedence over any other configured