Skip to content

HowTo_ddnsResourceRobustness.md

Latest commit

 

History

History
106 lines (98 loc) · 4.32 KB

HowTo_ddnsResourceRobustness.md

File metadata and controls

106 lines (98 loc) · 4.32 KB
Raw

How to improve robustness of ddns resource

Symptoms

  • You use ddns resource.
  • Cluster nodes does not have a permission to delete A Record for a target zone on DNS Server.
  • Failover fails for ddns resource activation failure.
  • On ddns resource Properties, "Delete the Registered IP Address" is not checked.

Cause

When ddns resource is activated Node-A, Node-A registers A Recod with ddns virtual hostname and Node-A IP address to DNS Server target zone.
At that time, Node-A who registered the A Record can have a permission for the A Record.
When ddns resource is failed over and activated on Node-B, Node-B tries to remove the existing A Record then register a new A Record with ddns virtual hostname and Node-A IP address.
However, Node-A has a permission to remove the existing A Record but Node-B does not have and removing fails.
(If Node-B has a permisson for the target zone, it can remove.)

Solution

By checking "Delete the Registered IP Address" on ddns resource Properties, when ddns resource is de-activated on Node-A for failover, Node-A who has a permission for the A Record delete the existing A Record. Therefore, Node-B do not have to remove the A Record and ddns resource can be activated on Node-B successfully.

However, if failover occurs for Node-A down, ddns resource will be activated on Node-B without de-activation on Node-A. This means that Node-B should remove the existing A Record and it will fail. Therefore, adding to ddns resource "Delete the Registered IP Address" setting, please add an application resource which removes the existing A Record with a specified account.

Preparation

  • Enable Powershell DNSServer command
    On both servers

    1. Start Windows Server Manager
    2. Add following Server feature:
      • Remoe Administration Tools
        • Role Administration Tools
          • DNS Server Tools

  • Prepare Account
    An account which fufilling the following conditions (hereinafter, this is called "DNS Account") is required.

    • The account has a permission to the target zone level to delete record
    • The account is enabled on all cluster nodes
      e.g.) Domain account which has a permmision for zone

  • Store scripts On both servers

    1. Copy the following 3 scripts to "C:\Program Files\EXPRESSCLUSTER\bin".
    2. Set RemoveRecord.ps1 parameters:
      • $dnsServerIp
      • $ddnsVirtualHostname
      • $dnsZoneName
        e.g.)
     # Set the following parameters #  
 $dnsServerIp = "192.168.10.10"  
 $ddnsVirtualHostname = "ddns-test"  
 $dnsZoneName = "test.local"  
 ################################

Configuration

  1. Add application resource and set as follow:
    • Info
      • Type: Application resource
    • Dependency
      Change the group resources Dependency from Before to After:
      • Before
        1. resources 1
        2. ddns resource
        3. resources 2
      • After
        1. resources 1
        2. application resource
        3. ddns resource
        4. resources 2
    • Recovery Operation
      • Recovery Operation at Activity Failure Detection
        • Retry Count: 2 time
        • Failover Threshold: 0 time
        • Final Action: No operation (active next resource)
      • Recovery Operation at Deactivity Failure Detection
        • Final Action: No operation (deactive next resource)
    • Details
      • Resident Type: Non-Resident
      • Start Path: RemoveRecord1.bat
      • Tuning
        • Start
          • Domain: Set the target domain name (e.g. test.local)
          • Accout: Set DNS Account
          • Password: Set DNS Account password (It will be encrypted)
  2. Edit ddns resource Properties
    • Dependency
      Change the group resources Dependency from Before to After:
      • Before
        1. resources 1
        2. ddns resource
        3. resources 2
      • After
        1. resources 1
        2. application resource
        3. ddns resource
        4. resources 2
    • Details
      • Delete the Registered IP Address: Check
  3. Apply the configuration

Note

Application resource takes some time to get activated for DNS Server operation command (Powershell Get-DnsServer/Remove-DnsServer command).

Reference

https://docs.microsoft.com/en-us/powershell/module/dnsserver/?view=win10-ps