1 DNS cache proxy
The Direct response field, under “DNS cache proxy stat”, lists how many DNS queries the GSLB ServerIron ADX has responded to using the DNS cache proxy feature instead of forwarding the queries to the DNS server. In this example, the GSLB ServerIron ADX has responded directly to client queries ten times with the best site address among those cached on the ServerIron ADX itself, instead of forwarding the request to the DNS server.
For information about the statistics in the DNS query intercept stat section, refer to “Displaying transparent DNS query intercept statistics” on page 101.
Combining the DNS cache proxy and DNS override features
When the DNS cache proxy feature is enabled, the GSLB ServerIron ADX has to query the authoritative DNS server at regular intervals, to refresh the IP address list for each domain configured for GSLB. You can eliminate the need for a backend DNS server, by combining the cache proxy feature with the DNS override feature.
When you enable the DNS override feature, you also need to configure an IP list for the required domains. The ServerIron ADX performs health checks on the IP addresses configured for the domains and directly responds to client queries by using the GSLB policy to select the best IP address from the IP list configured for the requested domain.
By combining the DNS cache proxy feature with the DNS override feature, you can configure the ServerIron ADX to directly respond to client requests, without ever consulting the authoritative DNS server.
NOTE
A GSLB ServerIron ADX does not contain all the features of a real DNS server and thus cannot completely replace the DNS server.
NOTE
Although you do not need a real DNS server when you combine DNS cache proxy with DNS override, you still need to configure a virtual IP address for the DNS server. Clients send queries to the virtual IP address.
For information about configuring DNS cache proxy, refer to “DNS cache proxy” on page 91. For information about configuring DNS override, see “Enabling DNS override” on page 33.
To add a virtual IP address to which the clients can send their DNS queries, enter a command such as the following:
ServerIronADX(config)# server
The command in this example adds IP address 209.157.23.87 as a virtual server. When clients send their DNS queries to this address, the ServerIron ADX processes the queries.
GSLB DNS type any query
DNS servers perform the translation between fully qualified domain names and IP addresses. DNS supports a number of record types such as IPv4 Address records (A records), IPv6 Address records (AAAA records), Name Server records (NS records), Mail Exchange (MX records), Canonical Name records (CNAME records) and so on.
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