client_time_receive should always be after originate_timestamp

[daxinc]

Hi, I wrote a simple program to send a NTP request to a local NTP server. The problem I found is that the client_time_receive is before originate_timestamp most of the time. If I ran 5 times, it happens 4 times.

Here's one of the output where client_time_receive is before originate_timestamp.

Complete NTP request:
	originate_timestamp=1656190742.9307978,
	receive_timestamp=1656190742.6455479,
	transmit_timestamp=1656190742.645609,
	client_time_receive=1656190742.6068008,
	offset=-0.12322092056274414
client_time_receive - originate_timestamp = -0.32399702072143555

Code:

require 'net/ntp'

LOCAL_HOST = 'localhost'

# measure NTP metrics by sending an NTP request to local host
def measure
  resp = Net::NTP.get(LOCAL_HOST)

  puts "Complete NTP request:\n\toriginate_timestamp=#{resp.originate_timestamp},\n\treceive_timestamp=#{resp.receive_timestamp},\n\ttransmit_timestamp=#{resp.transmit_timestamp},\n\tclient_time_receive=#{resp.client_time_receive},\n\toffset=#{resp.offset}"
  puts "client_time_receive - originate_timestamp = #{resp.client_time_receive - resp.originate_timestamp}"
end

measure

I also print out the client_localtime in the get method and the originate_timestamp in the response object. They should be exactly same, but not. The originate_timestamp is usually greater than client_localtime for about 0.17 second.