DNS change from SDDC UI succeeds, but fails to update the /etc/resolv.conf file and old DNS servers are observed to still be present

Products

• VMware SDDC Manager / VCF Installer

Issue/Introduction

After updating DNS configurations through the SDDC UI, you may notice this did not take affect in the /etc/resolv.conf file and the old DNS server IPs are still present, see example below: 

DNS change was successfully applied to child nodes such as ESXI and vCenter and reflected correctly in SDDC UI 

Environment

VMware Cloud Foundation 5.2.x

Cause

Broadcom engineering is aware of this issue affecting SDDC manager 5.2 and is currently investigating.

This behavior is no longer present in VCF 9.x and later as the DNS configuration mechanism has been completely overhauled.

Resolution

To resolve the issue please apply the following steps: 

1. Take a snapshot of the SDDC manager before making any changes.
2. Log into the SDDC manager through SSH with VCF and access root with:

   su -

3. Navigate to the /etc/systemd/ directory and edit the resolved.conf file with below command:

   vi resolved.conf

4. In the vi tool, press "i" to edit
5. Remove the line starting with "DNS=" that can be found under [Resolve]
6. Press "ESC" to leave the edit mode
7. Save the file and exit VI with:

   :wq!

8. Restart resolved:

   systemctl restart systemd-resolved.service

9. Verify that /etc/resolv.conf now contains the expected DNS entries.

 

Additional Information

Configure/Update DNS Server IP Address in SDDC Manager or the VCF Installer through Command Line  (Not applicable for SDDC manager 5.2.x)