ITEC 3210 M - Applied Data Communications and Networks Professor: Younes Benslimane, Ph.D. Midterm Exam February 11 th 2013 Instructions Duration: 1 hour 20 minutes Answer all questions No documentation / No calculator allowed Give short and clear answers (You add unnecessary content, I subtract marks!) Work independently Keep presentation neat Questions Max Mark Multiple Choice 25 True / False 25 Short Essay 30 Subnetting 20 TOTAL 100 Student Last Name, First Name: Student Number:
Multiple Choice (2.5 marks each): One choice (a, b, c, d, or e) is possible 1. Which of the following statement(s) about application architecture is (are) true? a. The current best practice is logical star b. Current options include physical star c. An option no longer available is physical bus d. All of the above 2. Selection criteria for network operating systems (NOS) include: a. Hardware and software compatibility, not Ethernet compatibility b. Network architecture(s) supported c. Nominal data rate(s) supported 3. Which of the following statement(s) about protocols is (are) true? a. TCP is used for connection-oriented transmissions b. UDP is used for reliable delivery of packets c. ARP is used by thin clients to obtain the address of the default gateway close to its subnet d. All of the above 4. Which of the following statement(s) about addressing and subnetting is (are) true? a. Subnetting is required for all networks b. MAC addresses are required for all networks c. Computers on the same subnet have the same net ID but computers with different MAC addresses cannot be on the same subnet 5. Which of the following statement(s) about the OSI and the TCP/IP models is (are) true? a. The 7 layers of the OSI model are the application, the presentation, the session, the transport, the network, the data link and the physical layer b. The 5 layers of the TCP/IP model are the application, the transport, the network, the data link and the physical layer c. In the OSI model, the application layer handles the transfer of data between applications while the presentation layer handles the segmentation of the message 2
6. If you are trying to log onto www.toronto.ca, a related DNS response message contains: a. The host name corresponding to www.toronto.ca b. The IP address corresponding to www.toronto.ca c. The MAC address corresponding to www.toronto.ca d. The IP address of the next router on shortest path to the server you are trying to log onto 7. Which of the following statement(s) about addressing is (are) true? a. NAT allows to use a set of IP addresses for internal traffic and a second set for external traffic b. IPv6 uses 128-bit addresses and is designed to allow more hosts to be connected to the Internet c. Layer-2 addresses are 48-bit addresses and are represented using dotted decimal notation 8. Which of the following statement(s) about network devices is (are) true? a. Hubs are layer-1 devices and switches are layer-2 devices b. Gateways are used to connect Unix-based networks to Windows-based networks c. Switches cannot be used for backbone networks 9. Which of the following statement(s) about network architecture is (are) true? a. Options available include client/server architecture and host-based architecture b. Options available for the client/server architecture include 2-tier and 3-tier architectures c. Well-designed web-based email solutions use the n-tier client/server architecture d. All of the above 10. Which statement BEST describes how switches operate? a. Switches rely upon router to tell them where to forward frames b. Switches read frames sent to them and decide to which port to send them out based on the sending computer s MAC address c. Switches rely upon the Ethernet protocol to tell them where to forward frames d. Switches read frames sent to them and decide to which port to send them out based on the receiving computer s MAC address e. Switches rely upon NICs to find the best path based on minimum hop count 3
True / False (2.5 marks each): One choice (a or b) is possible 1. Dynamic routing can be based on various criteria, including cost and traffic conditions 2. Distance vector algorithm uses several metrics for routing 3. Structured design requires breaking a network into each layer of the TCP/IP model 4. Full duplex transmissions reduce the chances of collisions but cannot eliminate them 5. Current cabling options include twisted-pair cables and optical fiber cables, and all these options are used to carry signals from a sending computer to a receiving computer 6. From the OSI model perspective, HTTP is a layer-1 protocol 7. Based on the forwarding algorithm, routers must send RARP requests before delivering packets to their final destination 8. Routers are layer-3 devices that can be used to move data between subnets and within subnets 9. NICs are part of both the physical layer and the data link layer 10. When it comes to a router s operations, the network layer information is the only information that changes at each hop on the way from the sending computer to the receiving computer 4
Short Essay (30 marks): a) Briefly define three (3) key non-redundant indicators of network performance. b) Briefly compare how the host-based architecture and the client/server architecture rate on each one of the three indicators above. Explanations in all 3 comparisons are required! 5
Subnetting (20 marks): Consider a class B address with a subnet mask of 255.255.255.192: 1) Clearly explain 2 major benefits of subnetting (6 marks) 2) What is the maximum number of subnets? Show your work (4 marks) 3) What is the maximum number of hosts on each subnet? Show your work (4 marks) 4) Briefly explain how the subnet mask is used in the implementation of the forwarding algorithm (Do NOT explain the forwarding algorithm) (6 marks) 6