HERE is the failure log

stderr:
  ssh: Could not resolve hostname chromeos4-row3-rack9-host5: Name or service not known
  Traceback (most recent call last):
    File "/usr/local/autotest/client/common_lib/test.py", line 804, in _call_test_function
      return func(*args, **dargs)
    File "/usr/local/autotest/client/common_lib/test.py", line 461, in execute
      dargs)
    File "/usr/local/autotest/client/common_lib/test.py", line 347, in _call_run_once_with_retry
      postprocess_profiled_run, args, dargs)
    File "/usr/local/autotest/client/common_lib/test.py", line 376, in _call_run_once
      self.run_once(*args, **dargs)
    File "/usr/local/autotest/server/site_tests/autoupdate_Rollback/autoupdate_Rollback.py", line 50, in run_once
      rollback_message=error_message)
    File "/usr/local/autotest/client/common_lib/cros/autoupdater.py", line 709, in verify_boot_expectations
      timeout=self.KERNEL_UPDATE_TIMEOUT, sleep_interval=5)
    File "/usr/local/autotest/client/common_lib/site_utils.py", line 964, in poll_for_condition
      value = condition()
    File "/usr/local/autotest/client/common_lib/cros/autoupdater.py", line 706, in <lambda>
      lambda: (self.get_kernel_tries(active_kernel_state) == 0
    File "/usr/local/autotest/client/common_lib/cros/autoupdater.py", line 404, in get_kernel_tries
      return self._cgpt('-T', kernel)
    File "/usr/local/autotest/client/common_lib/cros/autoupdater.py", line 377, in _cgpt
      kernel['kernel'], flag, dev)).stdout.strip())
    File "/usr/local/autotest/client/common_lib/cros/autoupdater.py", line 350, in _run
      return self.host.run(cmd, *args, **kwargs)
    File "/usr/local/autotest/server/hosts/ssh_host.py", line 283, in run
      ssh_failure_retry_ok)
    File "/usr/local/autotest/server/hosts/ssh_host.py", line 240, in _run
      raise error.AutoservRunError("command execution error", result)
  AutoservRunError: command execution error
  * Command: 
      /usr/bin/ssh -a -x     -o StrictHostKeyChecking=no -o
      UserKnownHostsFile=/dev/null -o BatchMode=yes -o ConnectTimeout=30 -o
      ServerAliveInterval=900 -o ServerAliveCountMax=3 -o ConnectionAttempts=4
      -o Protocol=2 -l root -p 22 chromeos4-row3-rack9-host5 "export
      LIBC_FATAL_STDERR_=1; if type \"logger\" > /dev/null 2>&1; then logger
      -tag \"autotest\" \"server[stack::get_kernel_tries|_cgpt|_run] ->
      ssh_run(cgpt show -n -i 4 -T \\\$(rootdev -s -d))\";fi; cgpt show -n -i 4
      -T \$(rootdev -s -d)"
  Exit status: 255
  Duration: 10.0292198658
  
  stderr:
  ssh: Could not resolve hostname chromeos4-row3-rack9-host5: Name or service not known
END FAIL	autoupdate_Rollback	autoupdate_Rollback	timestamp=1485531567	localtime=Jan 27 07:39:27	


Please look at crbug.com/672633 for the build details