Midterm Exam Course name: Computer Networks Model answer Exam number: Course Code: CSE401 Exam Date: 0X April 2018 Lecturer: Dr. Ahmed ElShafee Time Allowed: 60 minutes ID:.. Name:.... Essay MCQ Total 18 12 30-1 / 8 -
1. The following figure presents a PC called PC1 is connecting a website name www.site.com. Study the figure below and complete the following table that contains packet trip from PC1 to Website. Note: you may use Router name followed by port number as MAC address of router. 3 From/to Packet details grade 1 PC1 R3 Source PC1 Mac 192.213.21.5 Destination R3:P2 41.212.55.78-2 / 8 -
2 R3 R2 Source R3:P1 192.213.21.5 Destination R2:P2 41.212.55.78 3 R2 R1 Source R2:P1 192.213.21.5 Destination R1:P2 41.212.55.78 4 R1 Server Source R1:P1 192.213.21.5 Destination Server : MAC 41.212.55.78 5 Server R1 Source Server : MAC 41.212.55.78 Destination R1:P1 192.213.21.5-3 / 8 -
6 R1 R2 Source R1:P2 41.212.55.78 Destination R2:P1 192.213.21.5 7 R2 R3 Source R2:P2 41.212.55.78 Destination R3:P1 192.213.21.5 8 R3 PC1 Source R3:P2 41.212.55.78 Destination PC1:MAC 192.213.21.5-4 / 8 -
2. Explain the function of the loopback and collision-detection features of an Ethernet NIC in CSMA/CD algorithm (support your answer with figure). The loopback feature copies the transmitted frame back onto the receive pin on the NIC interface. The collision-detection logic compares the received frame to the transmitted frame during transmission; if the signals do not match, a collision is occurring. With full-duplex operation, collisions cannot occur, so the loopback and collision-detection features are purposefully disabled, and concurrent transmission and reception is allowed. - 5 / 8 -
MCQ Questions *Attempt all 10 questions, mark your answer in the following table # a b c d e grade 1 A 2 D 3 4 A 5 6 7 C 8 9 D 10 11 C 12-6 / 8 -
1 The process of a web server adding a TCP to a web page, followed by adding a TCP, then an IP, and then data link and trailer is an example of what? a. encapsulation b. Same-layer interaction c. The OSI model d. All of the above e. None of the above 2 Which of the following terms is used specifically to identify the entity that is created when encapsulating data inside data-link s and trailers? a. b. Chunk c. Segment d. Frame e. packet f. None there is no encapsulation by the data link layer 3 Which of the following best describes the main function of OSI Layer 1 protocols? a. Framing b. Delivery of bits from one device to another c. Addressing d. CSMA/CD e. Defining the size and shape of Ethernet cards 4 Which of the following are part of the functions of OSI Layer 2 protocols? a. Framing b. Delivery of bits from one device to another c. Addressing d. Error detection e. Defining the size and shape of Ethernet cards 5 Which of the following is true about Ethernet crossover cables? a. Pins 1 and 2 are reversed on the other end of the cable. b. Pins 1 and 2 connect to pins 3 and 6 on the other end of the cable. c. Pins 1 and 2 connect to pins 3 and 4 on the other end of the cable. d. The cable can be up to 1000 m to cross over between buildings. e. None of the above. 6 Which of the following are true about the CSMA/CD algorithm? a. The algorithm never allows collisions to occur. b. Collisions can happen, but the algorithm defines how the computers should notice a collision and how to recover. c. The algorithm works only with two devices on the same Ethernet. d. None of the above. A D A - 7 / 8 -
7 A is basically all of the components, hardware and software, involved in connecting computers across small and large distances. A. LAN. WAN C. Network D. SAN 8 A is used to connect networking devices that are in a very close geographic area, such as a floor of a building, a building itself, or a campus environment. A. WAN. LAN C. MAN D. LAN and MAN 9 Put the following in the correct order, from high to low: session (a), presentation (b), physical (c), data link (d), network (e), application (f), transport (g). A. c, d, e, g, a, b, f. f, a, b, g, d, e, c C. f, b, g, a, e, d, c D. f, b, a, g, e, d, c 10 Which of the following standards or protocols are used by the session layer? A. JPEG. NFS C. TCP D. Ethernet 11 The layer provides for hardware addressing. A. Transport. Network C. link D. Physical 12 CSMA/CD stands for. A. Collision Sense Multiple Access/Carrier Detection. Carrier Sense Multiple Access/Collision Detection C. Collision Sense Media Access/Carrier Detection D. Carrier Sense Media Access/Collision Detection C D C - 8 / 8 -