Communication networks engineering. (Question 2) ################
===========================================================================
--------------------------------------------------------------------------------------------------------------------------
uestion 2 T13 p Please, answer the following questions a) (3 pts) Describe the difference between the header lines RCPT TO: Kciao@anybody.edu> and To:
b) (5 pts) Compute the time it takes to a mail server to transfer two email messages to another mail server that contains the inbox mailboxes of the recipients of the two emails. Assume a network throughput of 1kbps, and propagation delay between the two servers equal to 0.5 seconds. Suppose that every message exchanged has negligible transmission delay, with the exception of the email messages that have 2000 characters each. (Assume the first message from the server arrives together with the TCP connection acknowledgement) c (5 pts) Download and read RFC 5321 for SMTP. Find and write what is a trace record, who inserts it, where, and what it contains. Consider the following received spam email data. Is this data contained in the final delivery? Why? Explain each line of the trace record from this email, and how you could notice that this is spam if compared to a non-spam email below. SPAM Delivered-To: mp@gmail.com Received by 10.25.33.201 with SMTP id h192csp2159645lfh; Mon, 22 Feb 2016 12:58:46 -0800 (PST) X-Received: by 10.50.43.134 with SMTP id w6mr12922059igl.22.1456174726771; Mon, 22 Feb 2016 12:58:46 -0800 (PST) Return-Path: kaaa@a.com Received: from anyone.edu (wlan-4-22.unl.edu. [129.93.4.22]) by mx.google.com with SMTP id r83si43127439ioi.61.2016.02.22.12.56.14 for ; Mon, 22 Feb 2016 12:58:46 -0800 (PST) Date: Mon, 22 Feb 2016 12:58:46 -0800 (PST) Message-Id: and To: b) (5 pts) Compute the time it takes to a mail server to transfer two email messages to another mail server that contains the inbox mailboxes of the recipients of the two emails. Assume a network throughput of 1kbps, and propagation delay between the two servers equal to 0.5 seconds. Suppose that every message exchanged has negligible transmission delay, with the exception of the email messages that have 2000 characters each. (Assume the first message from the server arrives together with the TCP connection acknowledgement) c (5 pts) Download and read RFC 5321 for SMTP. Find and write what is a trace record, who inserts it, where, and what it contains. Consider the following received spam email data. Is this data contained in the final delivery? Why? Explain each line of the trace record from this email, and how you could notice that this is spam if compared to a non-spam email below. SPAM Delivered-To: mp@gmail.com Received by 10.25.33.201 with SMTP id h192csp2159645lfh; Mon, 22 Feb 2016 12:58:46 -0800 (PST) X-Received: by 10.50.43.134 with SMTP id w6mr12922059igl.22.1456174726771; Mon, 22 Feb 2016 12:58:46 -0800 (PST) Return-Path: kaaa@a.com Received: from anyone.edu (wlan-4-22.unl.edu. [129.93.4.22]) by mx.google.com with SMTP id r83si43127439ioi.61.2016.02.22.12.56.14 for ; Mon, 22 Feb 2016 12:58:46 -0800 (PST) Date: Mon, 22 Feb 2016 12:58:46 -0800 (PST) Message-Id:
