1. Oracle ZFS Storage Appliance Administration Guide, Release OS8.8.x
  2. Appliance Services
  3. Configuring Services
  4. DNS Configuration
  5. DNS Health Check

DNS Health Check

The DNS health tool checks the validity of your DNS configuration. If an Oracle ZFS Storage Appliance system has an issue where DNS configuration is a suspect, the DNS health tool can help identify the problem or eliminate DNS configuration as a contributor to the problem.

In addition to checking the appliance where you are running the tool, you can specify a different hostname or IP address to check.

The DNS health tool identifies questionable configuration such as the following:

  • Missing or inconsistent DNS data such as missing A or PTR records or name mismatches between A and PTR records.

  • Issues with looking up public Internet names.

  • Issues with looking up nonexistent addresses.

  • Performance problems in queries.

The DNS health tool reports the possible configuration issues that it discovers as warnings rather than as errors because that configuration might be appropriate for a specific situation. Make sure you understand the warning and the specific situation of the system that is being tested.

The following are examples of configuration issues that the DNS health tool might not identify:

  • The tool cannot discover aliases, and so cannot discover issues such as the following:

    • Client references through CNAME records.

    • Names with A records that refer to the system, where those names do not appear in PTR records.

  • DNS configuration that is specific to Active Directory (AD); for example, the SRV records that are used to locate domain controllers.

In addition to printing warnings, the report that is produced by the DNS health tool describes the detailed steps that were taken to discover each configuration warning. For example, if the system's configured interface addresses include an address whose PTR record refers to a different name, the report will show a description such as the following:

WARN: 1.2.3.4 is b.example.com, expected a.example.com
    interfaces -> 1.2.3.4
    PTR 1.2.3.4 -> b.example.com

You can show all lookup operations that result in a reported warning. You can show all steps performed by the DNS health tool, not just the steps that result in a reported warning.