Brocade Communications Systems IP250 user manual Applying metrics on the Metrics tab

GSLB policy management 30

e.Select the tie breaker method from the Tie Breaker list. This value is used in case multiple addresses pass the policy criteria without one address emerging as the best choice:

•Least Response: Selects the address of the site that has been selected least often in previous DNS responses.

Note: ADX-type products do not support the Least Response tie-breaker method.

•Round Robin: Selects the first IP address in the DNS response for the first client request, then selects the next address for the next client request, and so on.

5.Provide the following additional information for Domain Name System (DNS) servers.

a.In the Check Interval field, indicate how often the GSLB ServerIron ADX product refreshes its zone and host information with DNS servers.

b.Select the TTL check box if you want the ServerIron ADX product to modify the Time to Live (TTL) value in DNS responses before sending the responses to the client DNS server.

c.If the TTL check box is selected, enter the number of seconds in the TTL Value field. The GSLB ServerIron ADX product changes the time to live (TTL) in each DNS record in the DNS responses before sending them to the client DNS server. If the TTL check box is not selected, the ServerIron ADX product does not change the TTLs, regardless of the value in this field.

d.Select the Active check box if you want the ServerIron ADX product to remove IP addresses obtained from DNS replies that fail a health check. The ServerIron ADX product removes these addresses as long as the DNS query contains at least one address that passes the health check.

By default, the GSLB ServerIron ADX product retains the same number of IP addresses in the DNS replies from the DNS server. The GSLB policy swaps the IP address on the top of the list with the best address selected by the GSLB policy.

e.If you do not want the default behavior, select the Best only check box to allow the ServerIron ADX product to remove all addresses except the one that the host-level GSLB policy selects as the best address.

f.Select the Cache Proxy check box if you want the ServerIron ADX product to act as a proxy for a DNS server, by responding directly to the client queries without forwarding them to the DNS server.

g.Select the Transparent Intercept check box if you want the ServerIron ADX product to either redirect or directly respond to client requests only for domains configured on the ServerIron ADX product. If the domain name requested by the client is not configured on the ServerIron ADX product, the query is forwarded to the DNS server without interception, and the reply is untouched by GSLB.

h.Select the CNAME Detect check box if you want the ServerIron ADX product to apply GSLB to Canonical Name (CNAME) records. A CNAME record refers to another domain name instead of an IP address.

i.Select the Override check box if you want the ServerIron ADX product to replace the IP address in the DNS reply with the IP address you configure for the proxy server.

Applying metrics on the Metrics tab

The GSLB ServerIron ADX product evaluates each IP address in the DNS reply based on the metrics order. Based on the results, the GSLB ServerIron ADX product can reorder the list to place the IP address for the best site on the top of the list.

Brocade Network Advisor IP User Manual	927
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