Readiness check fails for Ubuntu agents w/ resolv.conf error (4287517)

Readiness check fails for Ubuntu agents w/ resolv.conf error

The AD Readiness Check (or preflight script) is failling with the following error on an Ubuntu Linux machine:
  Check /etc/resolv.conf for proper formatting of nameservice            Failure
   entries and that the nameservers can be resolved
    Check hostname & DNS settings and that port 53 (TCP & UDP) is
     not firewalled: Failed to ping nameserver ERROR: in resolv.conf
    Check hostname or DNS and that port 53 (UDP & TCP) is not firewalled

The "ERROR:" in the message is from an unexpected response from the command "ping -c 1 <domainname>". The domainname should resolve to the name of a DC and so the DC should respond to the ping.

This could be caused by the wrong domainname being configured on the system, or by an issue in DNS. This has also could be caused by mDNS and so disabling mDNS in nsswitch.conf may resolve the issue.