You now have the ability to switch between BIND or Unbound resolvers on IB-4030-10GE appliances. Following are a couple scenarios for which you may consider using Unbound DNS resolution:

• To maintain optimum query performance in networks that have lower CHR (Cache Hit Ratio). For more information about CHR, see DNS Statistics for Cache Acceleration.
• To temporarily switch from BIND to Unbound when you encounter an unresolved vulnerability in BIND. Upon resolution of the vulnerability, you can switch back to BIND. For information about how to switch from BIND to Unbound and vice versa, see Configuring DNS Resolver Type below.

To use Unbound DNS, you must install the Dual Engine DNS license (in addition to the DNS Cache Acceleration license) on your IB-4030-10GE appliance. Contact your Infoblox representative to obtain these licenses. For information about how to install licenses, refer to the Infoblox NIOS Administrator Guide.

When you use Unbound as the DNS resolver, the appliance acts as a recursive-only name server. Before you use Unbound DNS resolution, ensure that you understand some of the limitations and ramifications. For more information, see Best Practices for Configuring Unbound DNS below.

Best Practices for Configuring Unbound DNS

Following are some guidelines for consideration before you use Unbound as the DNS resolver:

• When you configure your IB-4030-10GE to use Unbound DNS, it acts as a recursive-only name server and some of the NIOS features are not supported. For a list of unsupported features, see Unsupported NIOS Features for Unbound DNS below.
• In general, for all unsupported NIOS features for Unbound DNS, their corresponding functions and tabs do not appear in Grid Manager. However, this might not hold true in a Grid when Unbound is configured for only one member and there are other members not configured for Unbound. In this case, you might still be able to see some of the unsupported tabs and functions through Grid Manager.
• Unbound DNS supports only the default DNS view; it does not support other user-defined DNS views that are supported by BIND. When you switch from BIND to Unbound, the appliance falls back to the default DNS view configuration.
• You must restart DNS service each time you switch between Unbound and BIND in order for the configuration to take effect. Switching between Unbound and BIND might cause some service interruptions.
• Query results could be different when using BIND versus Unbound. For example, when you query the auto created zone "0.0.127.in-addr.arpa," query results for BIND and Unbound are as follows:
  BIND:
      ;; ANSWER SECTION:
    0.0.127.in-addr.arpa. 3600 IN SOA cluster. please_set_email.absolutely.nowhere. 2 10800 3600 604800 3600
  UNBOUND:
      ;; AUTHORITY SECTION:
    127.in-addr.arpa. 10800 IN SOA localhost. nobody.invalid. 1 3600 1200 604800 10800

For more information about Unbound specifications and how it works, refer to the Unbound documentation at https://www.unbound.net/documentation/index.html.

• There might be a few known general issues when configuring Unbound DNS resolution. Refer to the latest version of the NIOS 7.2.x release notes to review these issues.

Configuring DNS Resolver Type

To use Unbound as the DNS resolver:

1. Ensure that you have the Dual Engine DNS license installed on the appliance.
2. From the Data Management tab, select the DNS tab -> Members tab -> member check box -> Edit icon.
3. In the Member DNS Properties editor, click Toggle Advanced Mode.
4. When the additional tabs appear, click the General tab -> Advanced tab.
5. In the DNS Resolver Type section, select Unbound. To use the standard DNS resolution, select BIND. Note that when you switch between Unbound and BIND, the appliance preserves all relevant configurations.
6. Save the configuration and click Restart to restart DNS service.

Unbound DNS Logging

Logging is available when you select Unbound as the DNS resolver. However, the format and severity levels are different than that of the standard DNS logging. You can select the severity level for Unbound DNS logging, but you cannot configure logging facilities and categories—these functions will not be displayed in Grid Manager.
To configure the severity level for Unbound DNS logging:

1. From the Data Management tab, select the DNS tab -> Members tab -> member check box -> Edit icon.
2. In the Member DNS Properties editor, click Toggle Advanced Mode.
3. When the additional tabs appear, click the Logging tab -> Basic tab.
4. From the Logging Severity drop-down list, select one of the following:
   • Cache Misses: Logs client identification for missed caches.
   • Algorithm: Logs information at the algorithm level.
   • Query: Logs information at the query level.
   • Detailed Operations: Logs detailed information for operations.
   • Errors Only: Logs errors only.
     Note: The default is Detailed Operations. Infoblox highly recommends that you keep the default setting or select Errors Only. Selecting other options might result in large log files, which could possibly affect your system performance.
5. Save the configuration and click Restart to restart DNS service.

Unsupported NIOS Features for Unbound DNS

When you configure your appliance to use Unbound as the DNS resolver, the IB-4030-10GE acts as a recursive-only name server and some of the NIOS features are not supported. As a result, corresponding tabs and functions for these features do not appear in Grid Manager when Unbound DNS is configured.  The following table,  Table 4 lists NIOS features that are not supported for Unbound DNS.

Table 4 Unsupported Features for Unbound DNS

Configuring Hostname and Server ID Options for Unbound DNS

Unbound DNS supports the configuration of hostname bind directive and server-id directive options, which enables the appliance to return the hostname of the answering DNS name server in response to queries from clients in a DNS anycast configured environment. For information about how to configure the hostname bind directive and server-id directive options, refer to the Configuring Hostname and Server ID Options section in the Infoblox NIOS Administrator Guide.