Dell VxRail: change DNS Server IP using REST API

After completing the deployment of the VxRail infrastructure, you may need to change DNS Server IP to point it to a different DNS.

If you deploy a brand new VxRail infrastructure, a DNS server may not be available on the network.

Since the installation of the VxRail/vSAN heavily depends on the DNS, if no external DNS Servers are available during the deployment, an internal DNS in the VxRail Manager can be used.

Check current VxRail cluster DNS configuration

First thing to check is the current DNS Server in use by the VxRail.

From the preferred browser, access the following page:

https://<VxRail_Manager>/rest/vxm/api-doc.html#/operations/v1_system_dns_get

In the example the VxRail Manager IP is 10.127.200.12.

Enter the VxRail vCenter SSO authentication credentials (in the example administrator@vsphere.local) and click Send Request button.

The API client will authenticate and the 200 OK response returns the requested information. In the example, the current DNS Server IP is 10.127.200.12 and the VxRail Manager is configured tu use an internal DNS.

The configured DNS Server can be also checked in the vSphere Client. The Preferred DNS server in use has the same IP 10.127.200.12 value as the VxRail Manager.

How to change DNS Server IP in the VxRail cluster

To change DNS Server IP, from the preferred browser enter the address:

https://<VxRail_Manager>/rest/vxm/api-doc.html#/operations/v1_system_dns_post

To configure the new DNS settings, you need to enter the appropriated values accordingly:

Auth - make sure the correct VxRail vCenter SSO authentication credentials are entered.
vCenter - enter the administrator SSO username and password.
Components - specify which DNS Servers are updated. To replace all DNS Servers in the cluster enter ALL (default). To replace only the VxRail DNS, enter VXM.
Servers - enter the DNS IP addresses to use (in the example 10.129.25.11, 10.129.25.12).

Click Send Request button to replace the DNS IPs.

The operation may take some minutes depending on the number of ESXi hosts configured in the cluster. If the 200 OK response code is returned, the change DNS Server IP procedure succeded. Note the DNS in use is now reported as external.