> Source: [sk184436](https://support.checkpoint.com/results/sk/sk184436)

# sk184436 - DNS per-VS configuration loss on some Virtual Systems in VSX Cluster after failover or reboot

| Property | Value |
|----------|-------|
| Solution ID | sk184436 |
| Date Created | 2026-02-18 |
| Last Modified | 2026-02-19 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R81.20, R81.10 (EOS) |

## Symptoms

- * When using DNS per Virtual System (per-VS DNS) on a VSX cluster with more than two members, configured DNS settings may disappear after certain cluster operations. The following behavior may be observed:  
  After a failover, reboot, or *cpstop/cpstart* on the Active member, DNS configuration for one or more Virtual Systems is missing.  
* The issue affects both active and backup VSs but occurs most consistently on VSs in BACKUP state after a failover.  
* Running "*show dns* " from the affected VS context returns either no DNS configuration, or the DNS settings from VS0 instead of the per-VS configuration.  
* The issue is not limited to failover, it may also occur during network changes or other cluster state transitions.

## Cause

The root cause lies in a synchronization handling issue in VSX clusters with more than two members. When a VS transitions to BACKUP state, the backup member does not properly retain per-VS DNS configuration, causing those settings to be incorrectly removed.

## Solution

This problem was fixed. The fix is included starting from:

* [Check Point R82](https://support.checkpoint.com/results/sk/sk181127)

If you choose not to upgrade, [contact Check Point Support](https://www.checkpoint.com/support-services/contact-support/) to get a Hotfix for your version.

A Support Engineer will make sure the Hotfix is compatible with your environment before providing it.  
For faster resolution and verification, collect these files:

1. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Management Server involved in the case.
2. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Security Gateway / each Cluster Member involved in the case.

**Hotfix installation instructions:**   
Refer to [sk168597 - How to install a Hotfix](https://support.checkpoint.com/results/sk/sk168597).  

Administrators must manually reconfigure DNS to restore expected behavior.

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