Chapter 10: Local Area Networks

Transcription

1 Chapter 10: Local Area Networks MULTIPLE CHOICE 1. CSMA stands for: a. Client-Server Multi-Access c. Carrier Server Master Application b. Carrier Sense Multiple Access d. none of the above 2. The CD in CSMA/CD stands for: a. Carrier Detection c. Collision Detection b. Carrier Delay d. Collision Delay 3. The Internet is: a. a network of networks c. a very large CSMA/CD network b. a very large client-server network d. not really a network at all 4. Most LANs: a. are based on Ethernet c. use UTP cable b. use CSMA/CD D 5. Dumb terminals are still used: a. in token-passing networks b. in networks requiring central monitoring c. in networks that cannot provide central monitoring d. none of the above 6. In a circuit-switched network: a. communication is half-duplex only b. each channel carries only one data stream c. connection is usually done using a bus topology 7. Each computer on a network is called a: a. hub c. node b. token d. circuit 8. Compared to CSMA/CD systems, token-passing rings are: a. slower c. not as widely used

2 b. more expensive D 9. The key feature of a star network is that individual workstations are connected to: a. a central ring c. a node b. a central bus d. none of the above D 10. On networks, long messages are divided into "chunks" called: a. packets c. carriers b. nodes d. tokens 11. When two or more PCs try to access a baseband network cable at the same time, it is called: a. a collision c. excess traffic b. contention d. multiple access 12. When two PCs send data over a baseband network cable at the same time, it is called: a. a collision c. excess traffic b. contention d. multiple access 13. One type of network that never has a collision is: a. CSMA c. token-passing b. Ethernet d. all networks have collisions 14. In an Ethernet-based network, a switch can be used to reduce the number of: a. nodes c. packets b. users d. collisions D 15. The effect of too many collisions is: a. the network goes down c. the cable overheats b. the network slows down d. data is lost 16. MAU stands for: a. Multistation Access Unit c. Multiple Auxiliary Units b. Multiple Access Unit d. none of the above 17. The standard that describes Ethernet-type networks is: a. EIA 232 c. IEEE 802.3

3 b. IEEE d. CCITT ITU-E 18. Ethernet was invented by: a. IBM c. Xerox b. INTEL d. Digital Equipment Corporation 19. An Ethernet running at 10 Mbits / second uses: a. Manchester encoding c. NRZ encoding b. Three-Level encoding d. AMI encoding 20. A 100BaseT cable uses: a. fiber-optic cable c. RG-58U coaxial cable b. twisted-pair copper wires d. 50-ohm coaxial cable 21. The word "Base" in 10BaseT means: a. the cable carries baseband signals b. the cable has a base speed of 10 Mbps c. it can be used as the base for a backbone cable system d. none of the above 22. The reason a CSMA/CD network has a minimum length for packets is: a. to increase the data rate b. to prevent packets from reaching all other nodes during transmission c. to make sure all other nodes hear a collision in progress 23. The reason a CSMA/CD network has a maximum length for cables is: a. to increase the data rate b. to prevent packets from reaching all other nodes during transmission c. to make sure all other nodes hear a collision in progress 24. NIC stands for: a. Network Interface Card c. Network Interface Code b. Network Interface Cable d. Network Internal Code BaseT cable typically uses: a. a BNC connector c. an RJ45 connector

4 b. a T connector d. an RS11 connector 26. UTP stands for: a. Untwisted-Pair copper wire c. Uninterruptible Terminal Packet b. Unshielded Twisted-Pair copper wire d. Unicode Text Packet 27. Compared to twisted-pair telephone cables, CAT-5 cables: a. are cheaper c. allow faster bit rates b. are easier to crimp connectors onto 28. A hub: a. sends incoming packets out to all other terminals connected to it b. sends incoming packets out to specific ports c. cannot be used in an Ethernet-type network d. are more common in token-passing networks 29. A switch: a. sends incoming packets out to all other terminals connected to it b. sends incoming packets out to specific ports c. cannot be used in an Ethernet-type network d. are more common in token-passing networks 30. An advantage of using a switch instead of a hub is: a. it is cheaper when used in large networks b. it is faster when used in large networks c. it reduces the number of collisions in large networks 31. Broadband LANs: a. modulate the data onto a carrier b. use coaxial cables c. are provided by cable TV companies for Internet access D 32. Using one node in the network to hold all the application software is done in: a. peer-to-peer networks c. both a and b b. client-server networks d. none of the above

5 33. Record locking is used to: a. store records securely on a server b. prevent multiple users from looking at a document simultaneously c. prevent one user from reading a record that another user is writing to d. none of the above 34. The software that runs a client-server network must be: a. UNIX-based c. multitasking b. WINDOWS-based d. Novell certified 35. A "thin" client is: a. basically, a PC with no disk drives c. same as a "dumb" terminal b. a node that rarely sends data COMPLETION 1. A LAN is a Area Network. Local 2. The Internet is a network of. networks 3. In a network, all nodes are connected to a central computer. star 4. In a -switched network, users have a dedicated channel for the duration of communications. circuit 5. The of a network describes how it is physically connected together. topology 6. Ring networks often use -passing. token 7. A is a short section of a message in digital form. packet

6 8. is when two nodes try to seize the same cable at the same time. ontention 9. A occurs when two nodes transmit simultaneously on the same baseband cable. collision 10. In CSMA/CD networks, all collisions must be. detected 11. Carrier-Sense means that a node "listens" for the cable to be before using it. quiet free unused available 12. A " " cable links clusters of computers together. backbone BaseT cables can reliably carry up to bits per second. 100 mega 14. In CSMA/CD, packets must have a length to ensure that collisions are detected. minimum 15. In CSMA/CD, the of a cable is limited to ensure that collisions are detected. length 16. A unique numerical address is provided to a node by its. NIC 17. A 100BaseTX cable is a cable. fiber-optic 18. Hubs can be to form, in effect, one big hub. stacked 19. A switch looks at the of each incoming packet. address

7 20. The effect of a switch is to greatly reduce. contention SHORT ANSWER 1. Explain how a network can be a physical bus but a logical ring. A token-passing network sends the token from node to node in a prescribed order. So it doesn't matter how the physical connection is made. It still works like a token-passing ring. 2. What is the key difference between a hub and a switch? A hub sends incoming packets out to all other ports on the hub. A switch sends a packet to a specific port based on the address in the packet. 3. What is the advantage of a CSMA/CD network over a basic star network? If the central computer in a star network fails, the entire network is inoperative. If a node fails in a CSMA/CD network, it can be disconnected and the network still functions. 4. Why do CSMA/CD packets have a minimum size limit? If a packet is too short, nodes at either end of a cable could get on, send a packet, and get off before the packets travel far enough to collide. The collision would not be detected. 5. What is a NIC address, and why is it unique? The address is a long binary number "burned" into a NIC's memory chip at the factory. Each factory uses a different sequence of numbers, so the chances of two NICs on the same network having the same address is extremely small.