UDP Transport - Computer Networking - Old Exam Paper, Exams of Computer Networks

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Cork Institute of Technology

Higher Certificate in Computing in Information Technology Support – Award

(National Certificate in Computing in Information Technology Support – Award)

(NFQ – Level 6)

Summer 2005

Computer Networking

(Time: 2 Hours)

Answer any FOUR questions Examiners: Mr. D. Chambers All questions carry equal marks Mr. E. A. Parslow Mr. P. O’Connor Mr. T. Horgan

Question 1 Transport & Application Layers

a) Describe the main features of both the TCP and UDP transport protocols. (5)

b) What are port numbers and why are they necessary? List two ‘well known’ port numbers. (5)

c) What is the purpose of the TCP three-way handshake? Describe how this system works. (5)

d) Write a brief note about SMTP (Simple Mail Transfer Protocol). (5)

e) Briefly describe the purpose of each of the following TCP/IP utilities: (i) ipconfig/ifconfig, (ii) arp, (iii) netstat, (iv) route, (v) traceroute. (5)

Wide Area Networks

a) Write a brief note describing the channel service offered by the ISDN basic rate interface (BRI). (5)

b) Define each of the following ISDN terms:

i) Terminal Equipment Type 1 (TE1) ii) Terminal Equipment Type 2 (TE2) iii) Terminal Adapter (TA) iv) Network Termination Type 1 (NT1) v) Network Termination Type 2 (NT2) (5)

c) Describe how a Frame Relay network deals with congestion. (5)

d) What are Frame Relay PVCs and DLCIs and how are they used? (5)

e) Describe the basic method of mapping DLCI layer-2 addresses to IP addresses in layer 3? (5)

Question 3 – Distant Vector Routing a) Distance Vector routing protocols are prone to routing loops. Describe various ways of overcoming this problem. (5)

b) Would an extended ping from RTA, using the source IP address of 192.168.2.1, be able to ping 172.16.0.2 on RTB? Why or why not?

Assuming that RIP has now been configured, draw the routing tables for all three routers when the internetwork has converged. (5)

c) List the advantages and disadvantages of static routing. (5)

d) Define the following routing terms: Autonomous System, Administrative Distance, Default Route and Interior Gateway Protocol (IGP). (5)

e) Describe what happens when a packet is routed through an internetwork from source to destination. (5)

172.16.0.0/16 192.168.1.0/

.1 .2 .1.

RTA RTB RTC

192.168.2.0/

.1.

10.0.0.0/

e0 s0 s0 s1 s1 e

RTA#show ip route

C 172.16.0.0/16 is directly connected, Serial0/

Routers/Access Lists

a) State the purpose of each of the following router commands: (5)

i) show running-configuration ii) show version iii) show startup-configuration iv) enable secret class v) copy startup-config running-config

b) The router’s IOS has three principal modes: User, Privileged and Global Configuration mode. Give a brief description of each of these modes. What commands should be issued to access each mode? (5)

c) Describe the function and operation of both types of Access Control Lists (ACLs). (5)

d) With reference to the network shown below, create an access list and place it in the proper location to satisfy the following requirements: (5)

a. Prevent host 172.16.3.12 from accessing subnet 172.16.4. b. Prevents the outside world from accessing subnet 172.16.4. c. Allows all other hosts on all other subnets of network 172.16.0.0 (subnet mask 255.255.0.0) to access 172.16.4. (5) e) With reference to the network shown below, create an access list and place it in the proper location to satisfy the following requirements:

a. Deny only Telnet from subnet 172.16.3.0 to subnet 172.16.4.0. b. Permit all other traffic. (5)

LANs & VLANs

a) What are the benefits of LAN segmentation? Where can segmentation implemented? (5)

b) How does a transparent learning bridge filter frames? (5)

c) Outline the main differences between a LAN and a VLAN. (5)

d) IEEE 802.1q states that frame tagging is the way to implement VLANs. What is VLAN frame tagging and how does it operate? (5)

e) What is the difference between a Broadcast Domain and a Collision Domain? What devices are used to create these domains? (5)

Question 6 Subnetting

a) An organization has been assigned the network number 144.92.0.0 and it needs to create ten subnets. i) What is the default subnet mask for this network address? (2) ii) What is the broadcast address for this network? (2) iii) How many bits need to be borrowed from the host field when subnetting? (2) iv) What is the extended network mask after subnetting? (2) v) How many usable subnets are created after subnetting? (2) vi) How many valid host addresses are available in each subnet? (2) vii) What is the subnetwork address of the second usable subnet? (2) viii) What is the broadcast address of the second usable subnet? (2) ix) List the first and last valid host addresses of the fourth usable subnet. (2) x) What is the subnet address for host 144.92.110.223? (2)

b) Find the class of the following host addresses:

i) 12.255.255.255 (1) ii) 121.56.3.67 (1) iii) 192.23.98.12 (1) iv) 222.1.1.12 (1) v) 154.99.5.3 (1)