CS457/557 - Computer Networks - Spring 1997 Solutions to Exam 1


Computer Networks		CS 457                			NAME_______________
Spring 1997      		Test I					Dr. Wayne Summers

Read each question carefully before you answer.  Work at a steady pace,  and you should have ample time to finish.  Make sure your name is on your paper before you turn it in.  

I. Multiple Choice: Write the letter of the best answer. 

__c_____1. Which of the following is not a standards-making organization
a) ISO							b) ANSI
c) DARPA						d) IEEE
e) CCITT

___b____2. Which of the following is not a layer in the OSI reference model:
a) Application					b)Media Access
c) Session						d)Presentation
e) Transport

____a___3. Which of the following is a DTE:
a) computer						b) hub
c) modem						d) CSU/DSU
e) router

____c___ 4. To download a file means to:
        a) send data electronically from your terminal to another computer
        b) remove all control characters
        c) receive data electronically from another computer to your terminal/computer
        d) automatically dial your telephone number

____b___ 5. The standard measure of transmission speed is the
a) byte						b) baud
c) binary						d) cycle
e) frequency

____d__ 6. Digital signals are represented as
a) sine waves					b) oscillating waves
c) 1s and 2s						d) 1s and 0s
e) all of these

____a__ 7. FDM depends upon dividing up bandwidth into
a) several frequencies				b) formats
c) stop and start bits				d) cycles
e) none of these

____d___8. Which of the following are modulation techniques?
a) Phase Modulation				b) Amplitude Modulation
c) Frequency Modulation				d) all of these
e) none of these

____b___9. Which of the following would be used to detect errors?
a) Dynamic Speed Shifts				b) CRC
c) ARQ						d) all of these
e) none of these

____c___ 10. Which of the following is a reason for using a CSU/DSU instead of a modem? 
a) change from dial-up to leased line service	b) cheaper
c) change from analog to digital service		d) Dynamic Speed Shifts

____d___11. Teleconferencing is a substitute for
a) Pleasure travel					b) word processing
c) monitoring						d) business travel
e) none of these

____d___ 12.  Which of the following LANs uses the IEEE 802.3 standard?
a)  Compunet		    			b) Micronet
      	c)  Tokenet     					d) Ethernet
e) none of these

____a___ 13.  Which of the following is not a common LAN architecture?
a)  Branch						b)  Tree
      	c)  Mesh		     				d)  Ring
e)  Bus	

____c___ 14. The set of rules governing the flow of information in a  network is called
        a)  encryption          					b) multiplexing
        c)  protocol            					d) modem menu
        e)  packet switching

____b___ 15. A major advantage of fiber-optic transmission is its 
a) sensitivity						b) bandwidth
c) low cost						d) ease of installation
e) all of these

____c___ 16.   In the ______ topology, each node has equal access to a single line, much like a highway.
a)  star						b) ring
c)  bus       						d) tree
e) 	mesh

_____a___ 17.  LapLink and InterLink are examples of 
a)  Zero-slot LAN					b) Peer-to-peer LAN
      	c)  Client-Server LAN	     			d) WAN
e) VAN	

____a___18.  NETBIOS is
a) an API that interprets requests from the application and passes it along to the network operating system
b) data transfer technique that leaves the system CPU alone to process other applications
c) dedicated server software
d) sublayer of the OSI Reference Model
e) none of these

____a___19. The wiring center choice for a token ring network architecture is a
a) MAU						b) router
c) concentrator					d) multiplexer
e) bridge

____b___20. A disadvantage to using FDDI is 
a) speed						b) cost
c) reliability						d) security
e) none of these

____b___21. A computer that offloads the communications processing from a mainframe computer is called:
a) back-end processor				b) front-end processor
c) cluster controller					d) MUX
e) CSU/DSU

____d___ 22.  The device which connects two or more segments in a LAN is called a
a) gateway	    					b) router
      	c) bridge     						d) repeater
e) none of these	

____b___ 23.  The device which determines the most efficient path to transmit messages in a network and then sends the data along that path
a) gateway	    					b) router
      	c) bridge     						d) repeater
e) none of these	

____a__24.  The media type is determined at the __________ Layer of the OSI model
a)  Physical    					b) Data Link
      	c)  Network						d) Transport
e) 	none of these	

___e__ 25.   Which of the following is a reason for networking computers?
a) sharing hardware resources 			b) sharing files
      	c) sharing software					d) e-mailing
     	e)  all of these

II. Matching : Write the letter of the service name that would be most appropriate in the following situations:

A. P.O.T.S.		B. DS-0		C. T-1		D. T-3		E. ISDN

___e__ 26. A home user living in Albuquerque who wants high speed dial-up connectivity at a moderate price.
___c__ 27. A medium size organization (like Highlands) that wants fast connectivity to the Internet but at a moderate price.
___d__ 28. An ISP (Internet Service Provider) like TechNet that has a fiber-optic connection and wants a very-high speed connection to the Internet.

Write the letter of the OSI level that best describes the following:
A. Physical		B. Transport		C. Network		D. Presentation
E. Session		F. Data Link		G. Application

__f__ 29. IEEE 802 standards
__c__ 30. Router is used at this layer
__a__ 31. RS-232/V.24 interface

Write the letter of the equipment or wiring that would be used in the following situations:
A.  repeater		B. router		C. bridge 		D.  gateway
E.  hub       		F. Thinnet		G. Thick Ethernet	H.  UTP
I.  fiber-optic

__i__ 32.  Your network will be installed near one of your competitors offices.
__a__ 33.  You need to extend the distance of your LAN to a room 500 m away.
__f__ 34.  You been asked to install 10Base2.
Write the letter of the term or acronym described below:
 A. DCE      		B. DTE		C. BNC		D.  bps
E.  bpi       		F. network       	G. node    		H.  UART
I.   RS-232-C  	J. modem		K. CRC	       	L.  RBOC
M. LAN     		N. ppm 		O. CSU/DSU     	P. EIA-232-D
Q.  ACK/NAK	R. CSMA/CD		S.  ATM		T.   RJ-45

____J__ 35. Device which converts analog signals to digital and back.
____t__ 36. Connector used with UTP.
____f__ 37. Integration of computer systems, workstations and communications links.
____r__ 38. Ethernet
_____d_ 39. What would you measure the speed of data communications in?
___h__   40. Which device converts parallel bits into a serial stream of data?


IV. Answer completely only two of the following questions (10 pts each):

41.  Wagon Mound Elementary School wants to access the Internet in the classrooms. Discuss the various options they have for connecting to the Internet. Select the Abest@ option for them and write a brief rationale for why they should use your option.

a) 	dial-up connection using modems (limits the # of simultaneous connections) but cheap
b) 	direct connection (requires leasing a dedicated phone connection either to NMHU or an ISP)



42. a) My modem is an ACCURA 14.4+FAX14.4.  What does that mean?

ACCURA = brand name; 14.4 Kbps = speed of modem and speed of FAX 

b) The modem has the following specs.  Briefly explain the meaning of each.
i) V.32bis modulation

combination of phase shift modulation and amplitude modulation (Trellis coded modulation)  which provides for 14.4 Kbps


ii) V.42 error-control

incorporates MNP class 4 and LAP-M error control methods for data transmission


iii) V.42bis data compression

compresses data between 3.5:1 and 4:1 to increase speed of data communications


43. 	Draw a model of the OSI 7-layer model matching internetworking devices and protocols of various types to their corresponding OSI layers.
Application FTP, HTTP,SMTP, SNMP
Presentation
Session
Transport TCP, UDP, IPX
Network router IP, IPX
Data bridge IEEE 802.2, IEEE 802.3, IEEE 802.5
Physical repeater 10BaseT, 10Base2, 10Base5