Modifying gslb parameters related to dns responses – Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) User Manual
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Brocade Virtual ADX Global Server Load Balancing Guide
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Configuring GSLB protocol parameters
1
You can change the period to a value from 1 to 300 seconds. The GSLB Brocade Virtual ADX then
informs all the remote ADX devices of the change.
To change the GSLB protocol update period, enter the following commands on the GSLB Brocade
Virtual ADX.
Virtual ADX(config)#gslb policy
Virtual ADX(config-gslb-policy)#protocol status-interval 10
The command changes the GSLB protocol update period to 10 seconds.
Syntax: [no] protocol status-interval num
The num parameter specifies the number of seconds between status reports and can be from 1 to
300 seconds. The default is 30 seconds.
To display the current update period, enter the show gslb policy command. The interval is shown in
the Remote Brocade Virtual ADX status update period field. Refer to
on page 115 for more information.
Modifying GSLB parameters related to DNS responses
You can modify the following DNS-related GSLB parameters:
•
IP address for a site that fails a health check: Refer to
“Removing IP addresses for sites that fail
•
IP addresses that pass the health checks but still are not selected as the “best” site: By
default, the Brocade Virtual ADX leaves all the IP addresses in the DNS reply. You can configure
the Brocade Virtual ADX to remove all addresses from the reply except the “best” address.
Refer to
“Removing all addresses except the best address”
•
DNS record verification interval: Refer to
•
TTL value the Brocade Virtual ADX sets for the DNS records: Refer to
•
If you prefer to manage the TTL values solely using the DNS server, you can disable TTL
modification on the Brocade Virtual ADX. refer to
•
DNS override: Refer to
Removing IP addresses for sites that fail a health check
By default, the Brocade Virtual ADX does not remove an IP address from a DNS reply even if the
address fails a health check.
You can configure the Brocade Virtual ADX to remove IP addresses from DNS replies when those
addresses fail a health check. The Brocade Virtual ADX removes the addresses that fail the check
so long as the DNS query still contains at least one address that passes the health check.
A site must pass all applicable health checks (Layer 4 and Layer 7) to avoid being removed.
NOTE
If all the sites fail their health checks, resulting in all the sites being rejected by the GSLB Brocade
Virtual ADX, the Brocade Virtual ADX sends the DNS reply unchanged to the client.
When DNS active policy is enabled, there is a case where a client will still get an IP that failed a
health check. Therefore, when an IP list for a zone is configured, you need to also configure DNS
override on the GSLB policy.
The GSLB default behavior is as follows: