176 ServerIron ADX Global Server Load Balancing Guide
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Displaying GSLB information
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DNS override Indicates whether DNS override is enabled. DNS override replaces the
addresses in a DNS reply with the “best” address from a list of addresses you
configure. This field can have one of the following values:
•DISABLE: The ServerIron ADX does not replace the addresses in DNS
replies with an address from a list you configure.
•ENABLE: The ServerIron ADX replaces the addresses in DNS replies with
an address from a list you configure.
For more information about DNS override, refer to “Enabling DNS override” on
page 33.
Modify DNS response TTL Indicates whether the GSLB ServerIron ADX modifies the TTL in the DNS records
in DNS responses before sending the responses to the client’s DNS server. This
field can have one of the following values:
•DISABLE: The ServerIron ADX does not modify the TTLs.
•ENABLE: The ServerIron ADX modifies the TTLs.
DNS TTL Indicates the value (number of seconds) to which the GSLB ServerIron ADX
changes the TTL in each DNS record in the DNS responses before sending them
to the client’s DNS server.
NOTE: If the Modify DNS response TTL field contains “DISABLE”, the ServerIron
ADX does not change the TTLs, regardless of the value in this field.
DNS check interval Indicates how frequently the GSLB ServerIron ADX refreshes its zone and host
information with DNS servers.
Remote ServerIron ADX status
update period
Indicates how freque ntly the rem ote ServerIron ADXs send st atus updates to the
GSLB ServerIron ADX through the GSLB protocol.
Session capacity threshold Specifies how close to its maximum session capacity the site ServerIron ADX
(remote ServerIron ADX) can be and still be eligible as the best site for the
client. If a site ServerIron ADX exceeds the threshold, the site ServerIron ADX is
ineligible to be the best site.
Session capacity tolerance Specifies the percentage by which the number of available sessions on the site
ServerIron ADX can differ from the number of available sessions on another site
ServerIron ADX and still be considered an equally good site. Refer to “Site
ServerIron ADX’s available session capacity tolerance” on page 10.
Round trip time tolerance Specifies the percentage by which the RTT for one site can differ from the RTT
for another site without this metric resulting in selection of one site over the
other.
Round trip time explore
percentage
Indicates the percentage of client requests from a given network for which the
GSLB ServerIron ADX intentionally ignores the RTT metric when evaluating the
IP addresses in the DNS reply. The explore percentage prevents the ServerIron
ADX from continually biasing its site selection based on the first ServerIron ADX
to return RTT information. Refer to “Modifying round-trip time values” on
page 53.
Round trip time cache prefix Indicates the length (number of significant bits) of entries in the GSLB
ServerIron ADX’s IP address cache. The prefix determines the extent to which IP
addresses are aggregated into entries in the cache.
Round trip time cache interval Indicates how many seconds the GSLB ServerIron ADX keeps an unrefreshed
RTT cache entry in its cache before the entry ages out.
TABLE 13 GSLB policy information (Continued)
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