The IB-4030 and IB-4030-10GE are high-performance DNS caching-only name servers. Using DNS cache acceleration services, DNS query resolution can be more responsive for resolvers across the network. The appliance can be part of an Infoblox Grid or operates as an independent DNS caching appliance. The IB-4030 and IB-4030-10GE appliances support DNS queries on the LAN1, LAN2, MGMT, and HA ports.
illustrates a basic implementation of the IB-4030 or IB-4030-10GE. In , the network uses an IB-4030 or IB-4030-10GE appliance in an optimized deployment through the LAN1, LAN2, and MGMT ports, in which the appliance caches DNS responses for the Intranet and for resolvers in the Internet. The IB-4030 or IB-4030-10GE operates as a member of the Infoblox Grid, and responds to DNS requests from its cache, offloading that work from the authoritative servers. DNS requests, whose responses are not currently cached, are passed on to the authoritative servers, and their responses are returned to and cached by the IB-4030 or IB-4030-10GE appliance.
The DNS resource records are kept in its cache until they expire. The appliance uses the cache pre-fetch option to detect cached records that are about to expire and fetch another copy before actual expiration. When a query asks for data that has been cached, in addition to returning the data, the appliance fetches a fresh copy from the authoritative server if the pre-fetch condition (Eligible and Trigger settings) is met. This option helps minimize the time window in which no answer is available in the cache. The pre-fetch option is controlled by the following parameters:
- Eligible – The records that arrive with TTL greater than the eligible value are considered for pre-fetch. The default value is 9 seconds.
- Trigger – The TTL value at which pre-fetch takes place. The default value is 2 seconds.
The pre-fetch option is enabled by default and currently you cannot configure the Eligible and Trigger values. Configuration for these values might be supported in future releases.
Note: The pre-fetch option is not supported on servers that use Unbound as the DNS resolver.
Figure 1. IB-4030 or IB-4030-10GE Grid Installation
You can deploy the IB-4030 or IB-4030-10GE as an independent Infoblox appliance. A simplified example of which is shown in Figure 2.
Figure 2. IB-4030 or IB-4030-10GE as an Independent Appliance
You can deploy two IB-4030 or IB-4030-10GE appliances of the same model to form an HA pair, as shown in Figure 3. Note that only the active node in an HA pair handles DNS traffic. The passive node is in a standby mode ready to take over if a failover occurs. Note that the passive node does not operate with a pre-loaded cache or hot cache during a failover; it builds up the DNS cache over time. For information about how to configure an HA pair, refer to Chapter 5 Deploying a Grid in the Infoblox NIOS Administrator Guide.
Note: A reset of the cache acceleration card on the active node of an HA pair can trigger an HA failover.
Figure 3. IB-4030 or IB-4030-10GE as an HA Pair
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