Configure Access Zone DNS Dual Delegation
Introduction
This guide explains how to configure DNS Dual Delegation for Access Zone Failover in a PowerScale environment. DNS Dual Delegation ensures seamless client access to PowerScale storage clusters during failover scenarios. It works by delegating DNS queries for specific Access Zone SmartConnect names to both the primary and secondary clusters. This setup allows DNS resolution to automatically point clients to the appropriate cluster without requiring manual intervention during a disaster recovery event.
Unsupported Configurations
Certain DNS configurations are not supported or recommended for use with SmartConnect zones in PowerScale environments. These configurations can lead to issues with DNS resolution and failover functionality. Below are the unsupported practices and their associated considerations:
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DNS Forwarding
- DNS forwarding is not tested and is not recommended as a method to manage SmartConnect zone resolution.
- Instead, use Name Server (NS) delegation, which is the recommended approach for configuring DNS servers. This method is commonly used with DNS management systems such as Infoblox.
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Disabling Recursive Queries
- Disabling recursive queries on your DNS server is not recommended and remains untested in this context. Recursive queries are necessary for proper DNS resolution across multiple levels of the DNS hierarchy.
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Using CNAME Records for SmartConnect Zones
- Avoid using CNAME records that point to SmartConnect names. Additionally, do not create configurations that introduce circular references, such as CNAME records pointing to other resource records.
- According to Dell Isilon documentation, using CNAME records for SmartConnect zones is explicitly discouraged. Refer to Dell Technologies Isilon Advanced Networking Fundamentals for further details on best practices.
Using unsupported configurations can lead to unpredictable behavior and hinder failover and disaster recovery processes. Always adhere to the recommended practices to ensure reliable DNS resolution and seamless failover functionality.
How to Set Up Dual Delegation
DNS Return Codes
| DNS Return Message | DNS Response Code | Function |
|---|---|---|
NOERROR | RCODE: 0 | DNS Query completed successfully |
FORMERR | RCODE: 1 | DNS Query Format Error |
SERVFAIL | RCODE: 2 | Server failed to complete the DNS request |
NXDOMAIN | RCODE: 3 | Domain name does not exist |
NOTIMP | RCODE: 4 | Function not implemented |
REFUSED | RCODE: 5 | The server refused to answer for the query |
YXDOMAIN | RCODE: 6 | Name that should not exist, does exist |
XRRSET | RCODE: 7 | RRset that should not exist, does exist |
NOTAUTH | RCODE: 8 | Server not authoritative for the zone |
NOTZONE | RCODE: 9 | Name not in zone |
See Also
See the Access Zone Failover Guide for more information about SmartConnect Zone names and aliases, and other configuration steps and considerations for the failover process.