Question 1

Madeline travels all day and all night around the United States and no matter where she goes, her IP address is always the same. What technology is this?

Accepted Answer

Mobile IP technology allows a user to move from one network to another and still use the same IP address. It is an improvement upon the IP protocol because it allows a user to have a home IP address associated with his home network and care-of address. The care-of address changes as he moves from one network to the other. All traffic that is addressed to his home IP address is forwarded to his care-of address.

Question 2

Protocols determine how computer systems communicate across networks through encapsulation. What is true about encapsulation?

Accepted Answer

Protocols determine how computer systems communicate across networks through encapsulation, which allows for the building of a message through protocol stacks. A message is constructed within a program on one computer and then passed down through the protocol's stack. A protocol at each layer adds its own information to the message; thus, the message grows in size as it goes down the protocol stack. The message is then sent to the destination computer and the encapsulation is reversed by taking the packet apart through the same steps used by the source computer that encapsulated it.

Question 3

A protocol at each layer has specific responsibilities and functions that it must perform. What layer does not include an application, but rather, the protocols that support applications?

Accepted Answer

The application layer does not include an application, but rather, the protocols that support applications. This layer works closest to the user and provides file transmissions. When an application needs to send data over the network, it passes instructions and the data to the protocols that support it at the application layer. This layer processes and properly formats the data and passes the same down to the next layer within the OSI model.

Question 4

A protocol at each layer has specific responsibilities and functions that it must perform. What layer allows for communication between two applications?

Accepted Answer

The session layer allows for communication between two applications. It is responsible for establishing a connection between the two applications, maintaining it during the transfer of data, and controlling the release of these connections. The session layer protocol can enable communication between the two applications by three different modes 1) Simple is communication that takes place in one direction. 2) Half-duplex allows communication to take place in both directions, but only one application can send information at one time. 3) Full-duplex allows communication to take place in both directions and both applications can send information at the same time.

Question 5

A protocol at each layer has specific responsibilities and functions that it must perform. What layer formats application layer protocols in the OSI model?

Accepted Answer

The presentation layer formats application layer protocols into the OSI model. This layer provides a common means of representing data in a structure that can be properly processed by the end system. The presentation layer is not concerned with the meaning of data, but with syntaxes and format of those data. It works as a transporter, translating the format an application is using to a standard format used for passing messages over a network. This layer also handles data compression and encryption.

Question 6

What are the two main protocols that work at the transport layer?

Accepted Answer

TCP and UDP are the two main protocols that work at the transport layer. TCP is a reliable and connection-oriented protocol, thus it ensures packets are delivered to the destination computer. If a packet is lost during transmission, TCP has the ability to identify the issues and resends the lost or corrupted packet. TCP also supports packet sequencing, flow, congestion control, and error detection and correction. UDP is a best-effort and connectionless protocol. It has neither packet sequencing nor flow and congestion control, and the destination does not acknowledge every packet it receives.

Question 7

Henry's computer is sending information by dividing it into small, logical, and more tangible network segments. What is Henry's computer doing?

Accepted Answer

Subnetting divides information into small, logical, and more tangible network segments. This reduces traffic loads across a network and the possibility of network congestion and excessive broadcast packets. Subnetting is especially beneficial in keeping down routing tables sizes because external routers can directly send data to the actual network segment without having to be concerned about the internal architecture of that network and getting the data to individual hosts.

Question 8

What types of transmission signals are continuously varying electromagnetic waves?

Accepted Answer

Analog transmission signals are continuously varying electromagnetic waves. These waves are carried over air, water, twisted-pair cable, coaxial cable, and fiber-optic cable. Through a process of modulation, data are combined with a carrier signal of a specified frequency. The carrier signals provide many radio station frequency ranges and communication channels. Each radio station is given a certain carrier signal and frequency to use for transmissions. This is different from digital signals, which are binary digits as electrical pulses.

Question 9

What type of transmission signals are binary digits as electrical pulses?

Accepted Answer

Digital transmission signals are binary digits as electrical pulses. Each individual pulse is a signal element and represents either a 1 or a 0. Digital signals are more reliable than analog signals over a long distance and provide a clear-cut and efficient signaling method. Digital signals can easily be extracted from noise and retransmitted. Digital signals are a square wave, which does not have all the possible values of the different amplitudes and frequencies of an analog signal. Digital systems are superior to analog systems because they can transport more calls and data transmission on the same line at higher quality over longer distances.

Question 10

What technology has a control frame that travels in a logical circle and is "picked up" when a system needs to communicate?

Accepted Answer

The Token Ring is technology that has a control frame that travels in a logical circle and is "picked up" when a system needs to communicate. This allows communication and sharing of networking resources with a star-configured topology that is called a Multistation Access Unit. The token-passing technology is one in which a device cannot put data on the network wire without having possession of a token. This is different from Ethernet, in which all the devices attempt to communicate at the same time, which is why Ethernet is referred to as a "chatty protocol" and has collisions. Token Ring does not endure collisions, since only one system can communicate at a time, but this also means communication takes place more slowly.

Question 11

What was developed by the American National Standards Institute as high-speed token-passing media accessing across technology?

Accepted Answer

The Fiber Distributed Data Interface (FDDI) was developed by the American National Standards Institute as high-speed token-passing media accessing across technology. FDDI has a data transmission speed of up to 100 Mbps and is usually used as a backbone network using fiber-optic cabling. It also provides fault tolerance by offering a second counter-rotating fiber ring. The primary ring has data traveling clockwise and is used for regular data transmission. The second ring transmits data in a counterclockwise fashion and is invoked only if the primary ring goes down. Sensors watch the primary ring and if it goes down, they invoke a ring wrap so the data will be diverted to the second ring. Each node on the FDDI network has relays that are connected to both rings, so if a break in the ring occurs, the two rings can be joined.

Question 12

Marsha can't find anything wrong with her computer, but there seems to be a disruption taking place that is causing data corruption. Where would this disruption come from?

Accepted Answer

Cabling can cause disruptions that lead to data corruption. When cabling problems occur, the entire network can experience disruption. There are three major problems that can cause disruption. First, noise on a line is usually caused by surround devices or by characteristics of the wiring's environment. Noise can be caused by motors, computers, copy machines, fluorescent lighting, etc. These interferences can combine with the data being transmitted over the cable and distort the signal. Next, attenuation is the loss of signal strength as it travels. The longer the cable, the more attenuation is introduced, which causes the signal carrying the data to deteriorate. Once data travels over a certain distance, the resistance of electron flow aggregates and destroys the integrity of the signal. Last, crosstalk occurs when electrical signals of one wire spill over to another wire. When different electrical signals mix, their integrity degrades and data corruption can occur.

Question 13

Neal and Bob are working on an Ethernet network and are trying to send information at the same time. What can happen to the network?

Accepted Answer

When two computers on an Ethernet network are trying to send information at the same time, a collision can occur. Other computers on the network will detect the collision because the overlapping signals of the collision increase the voltage of the signal above a specific threshold. The more devices on a contention-based network, the more likely collisions will occur, which increases network latency or data transmission delays. An unacceptable amount of collisions can be caused by a highly-populated network, a damaged cable or connector, too many repeaters, or cables that exceed the recommended length.

Question 14

What control method delivers status messages, report errors, and is used to test connectivity?

Accepted Answer

Internet Control Message Protocol (ICMP) delivers status messages, report errors, and is used to test connectivity. ICMP also indicates when problems occur with a specific route on the network and tells surrounding routers about better routes to take based on the health and congestion of the various pathways. Routers use ICMP to send messages in response to data grams that could not be delivered. ICMP is used by other connectionless protocols, not just IP, because connectionless protocols do not have any way of detecting and reacting to transmission errors, as do connection-orientated protocols. Under these conditions, the connectionless protocol may use ICMP to send error messages back to the sending system to indicate networking problems.

Question 15

The two main types of routing protocols are used to make routing decision based on either distance-vector routing protocols or link-state routing protocols. However, there are a handful of De facto and proprietary interior protocols in use. Which De facto protocol uses link-state algorithms to send out routing table information?

Accepted Answer

Open Shortest Path First (OSPF) is a De facto protocol using link-state algorithms to send out routing table information. The use of algorithms allow for smaller, more frequent routing table updates to take place. This provides a more stable network than Routing Information Protocol, but requires more memory and CPU resources to support the extra processing. OSPF allows for a hierarchical routing network that has a backbone link connecting all subnets together.

Question 16

The two main types of routing protocols are used to make routing decisions based on either distance-vector routing protocols or link-state routing protocols. However, there are a handful of De facto and proprietary interior protocols in use. Which De facto protocol was created by Cisco Systems and uses five criteria to make a decision?

Accepted Answer

The Interior Gateway Routing Protocol (IGRP) was created by Cisco Systems and uses five criteria to make a decision. IGRP is a distance-vector routing protocol. Routing Information Protocol uses one criterion to fine the best path between the source and destination and IGRP uses five criteria to make a "best route" decision. A network administrator can set weights on these different metrics so that the protocol works best in that specific environment.

Question 17

There are several devices used in LANs, MANs, and WANs that provide communication between networks and computers with functionalities, intelligences, network placement, and capabilities. Which device provides the simplest type of connectivity?

Accepted Answer

Repeater devices provide the simplest type of connectivity. Repeater devices are the simplest because they only repeat and amplify electrical signals between cables segments, which enables them to extend a network. Repeaters work at the physical alert and are add-on devices for extending network connection over a greater distance. The device amplifies signals because signals attenuate the further they have to travel. Repeaters can also work as line conditioners by cleaning up the signals. This works much better when amplifying digital signals than when amplifying analog signals, because digital signals are discrete units, which makes extraction of noise from them much easier for the amplifier.

Question 18

LAN technologies are used to communicate over a small geographic area. What is used to communicate over large geographical areas?

Accepted Answer

WAN, or wide area network, is technology that is used to communicate over a large geographical area. WAN traffic may have to travel hundreds or thousands of miles and pass through several different types of devices, cable, and protocols. Because of this difference, most LAN MAC protocols are connectionless and most WAN communication protocols are connection oriented. Connection-oriented protocols provide reliable transmission because they have the capability of error detection and correction.

Question 19

Dedicated links have a single transverse, thus needing to know only two points of reference for delivering packets. When thousands of networks are connected to each other, switching is used. What type(s) of switching is/are there?

Accepted Answer

There are two types of switching: circuit and packet. Circuit switching sets up a virtual connection that acts like a dedicated link between two systems. When the source system makes a connection with the destination system, they set up a communication channel. If the two systems are local to each other, few devices need to be involved with setting up this channel. The farther the two systems are from each other, the more the devices are required to be involved with setting up the channel and connecting the two systems. Packet switching does not set up a dedicated virtual link and packets from one connection can pass through a number of different individual devices instead of all of them following one another through the same devices. The infrastructure that supports these methods is made up of routers and switches of different types. They provide multiple paths to the same destinations.

Question 20

What type of high-speed connection technology provides up to a 52-Mbps transmissions speed without replacing the carrier's copper wire?

Accepted Answer

Digital Subscriber Line (DSL) is a type of high-speed connection technology that provides up to a 52-Mbsp transmissions speed without replacing the carrier's copper wire. It can provide 6 to 30 times higher bandwidth speeds than ISDN and analog technologies. It uses existing phone line and provides a 24-hour connection to the Internet. However, both the carrier and the end user must have upgraded equipment for DSL. DSL provides faster transmission rates because it uses all of the available frequencies available on a voice-grade UTP line.

Quiz 3: Communication