VxRail – Flush DNS Cache

If modifying ESXi hostnames or management IP addresses a flush of both vCenter and VxRail cache services are needed, or if for some reason you are experiencing name resolution issues in your VxRail environment one useful troubleshooting task is to perform a flush of the local DNS cache on both the vCenter VCSA and VxRail manager. This post details how to clear the VxRail manager cache, for instructions on how to clear vCenter VCSA cache please refer to:

https://davidring.ie/2019/12/16/vmware-vcsa-6-7-clear-cache/

Begin by SSH to VxRail Manager and su to root. The command used to clear the DNS cache on VxRail Manager:

service dnsmasq restart

Checking service status after restart:

service dnsmasq status

Use dig @localhost hostname to verify hostname and IP mappings are correct:

It may also be worth checking /etc/hosts for any unexpected entries(which of course there should be none as this file is not to be modified) as dnsmasq will query the contents of /etc/hosts during a DNS query:

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