CENC400 Communication Networks Assessment 2026 | University of Dubai

CENC400 Assessment

Course Learning Outcomes (CLO)

This Instrument assesses the following Course Learning Outcomes (CLO):

• Explain the functionality of modern communication network layers.

Question 1 [5 marks]

Choose one of the following Coursera courses and complete it: 

• The Bits and Bytes of Computer Networking
• Connect and Protect: Networks and Network Security

Upon completion of the course, submit the certificate of completion (in a separate PDF) that meets the following criteria:

• Clearly shows your full name
• Displays the course title
• Includes the date of completion

From the course you completed, choose one specific lecture topic or real-world example (e.g., DNSlookup, TCP congestion control, BGP routing, SSL/TLS handshake, DDoS mitigation, QUIC protocol, etc). Then:

1.[2.5 marks] Reconstruct what happens across at least three network layers (naming each one) whenthat mechanism or protocol is executed.

• For example, if you pick “TCP congestion control,” explain howtransport, network, and data link layers are involved.
• Be specific about which layer provides what functionality in that scenario.

2. [2.5 marks] Reflect on how the lecture either reinforced or challenged the layered model taught in our class. Did you notice:

• Any inter-layer dependencies that weren’t obvious before?
• Any violations or workarounds that suggest a more flexible model?

You must:

• Use a concrete moment from the Coursera course (quote, diagram, or scenario)
• Connect that moment to the purpose of the layered model (modularity, encapsulation, abstraction)
• Critically comment on whether the layered abstraction is still appropriate or needs to evolve.

Additional Notes:

• Make sure you enrol in the course using your University of Dubai account for free access.
• If you face any technical issues, contact the instructor in advance

Question 2 [2 marks]

A file consisting of 3600 bits needs to be transmitted over the Internet. The data is first processed by the transport layer, which adds a 200-bit header, then passed to the network layer, which appends a 160-bit header. The resulting packets are transmitted through three networks, each of which adds a 24-bit header. The destination network imposes a maximum transmission unit(MTU) of 1000 bits, meaning no packet larger than 1000 bits (including all headers) can be transmitted on the final link.

What is the total number of bits, including all headers, delivered to the destination network after fragmentation?

[Assume that fragmentation occurs only at the network layer and that the transport and network layer headers appear only once (before fragmentation). You may assume no padding or alignment constraints.]

Question 3 [3 marks]

The Software Engineering team at your company has been allocated the following IP block:192.168.12.34/271.

1.[1 mark]Calculate the following:

a)Network address
b)Broadcast address
c)Subnet mask
d)Maximum number of usable host addresses in this subnet

2.[2 marks] The team currently has 19 employees, each needing a wired and wireless connection, plus 3 printers, 2 servers, and 2 IP-based security cameras. Will this subnet be sufficient? Show calculations. If not, what subnet mask would you propose instead?