title: Old-duplicate data packets in TFTP protocol
body: <p>I found this question in Book called An Introduction to Computer Networks by Peter L Dordal, and I met with this question which I found it a little bit tricky:</p>
  
  <p>In the TFTP protocol:</p>
  
  <p>If the client changes its port number on a subsequent connection, but the server does not, what prevents an old-duplicate data packet sent by the server from being accepted by the new client?</p>
  
  <p>If the server changes its port number on a subsequent connection, but the client does not, what prevents an old-duplicate data packet sent by the server from being accepted by the new client?</p>
  
  <p><a href="http://intronetworks.cs.luc.edu/current/html/udp.html?highlight=cumulative#old-duplicate" rel="nofollow noreferrer">http://intronetworks.cs.luc.edu/current/html/udp.html?highlight=cumulative#old-duplicate</a></p>