Final Exam

What are Field, Record, and File?

- A field is a single piece of information. - A record is one complete set of fields - A file is a collection of records. - For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number.

What are the limitations of storing files with single directory per volume approach?

- A very long time to search for a file. - The directory space needs to be filled before the disk storage space is filled. - Subdirectories will not be created. - Difficult to storage with some protection. - Every file needs a different name.

What are the benefits of using RAID?

1. Benefits: - A disk drive set that is a single unit logically. - Used to improve the oral I/O performance to be able to read and write from multiple disks with improves your I/O performance. - Good for data recovery, redundancy, and come up with a more reliable system. 2. Limitations: - Expensive due to mirroring which keeps an additional copy and disk expending where you expend data onto multiple disks.

What is a file descriptor? What all does it contain?

A file descriptor is a number that uniquely identifies an open file in a computer's operating system. It describes a data resource, and how that resource may be accessed. When a program asks to open a file — or another data resource, like a network socket — the kernel: Grants access.

What is a mesh network?

A mesh network is a local network topology in which the infrastructure nodes connect directly, dynamically and non-hierarchically to as many other nodes as possible and cooperate with one another to efficiently route data from/to clients.

What are Datagrams?

A packet

What is a protocol?

A standard that specifies the format of data as well as the rules to be followed during transmission

How does an access control matrix work? What are its advantages and disadvantages?

Access Matrix is a security model of protection state in computer system. It is represented as a matrix. Access matrix is used to define the rights of each process executing in the domain with respect to each object. The rows of matrix represent domains and columns represent objects

What does an access control list work? What are the advantages and disadvantages?

Access control lists (ACLs) perform packet filtering to control the movement of packets through a network. Packet filtering provides security by limiting the access of traffic into a network, restricting user and device access to a network, and preventing traffic from leaving a network.

What are the advantages and limitations of contiguous storage?

Advantages: You know the starting point and size and can be easily accessed. Disadvantages: Cannot resize files.

What are some variants of social engineering attacks?

Baiting. Scareware. Pretexting. Phishing. Spear phishing.

What are the differences between wired and wireless networks?

Bandwidth different wired is 1 Tbps and wireless is mbps, cost difference, wired needs cables, wireless just needs access points, wireless is less secure and wired is more secure, collision detection is difficult for wireless. CSMA/CA is used for wireless and CSMA/CD is used for wired

How does the source host find out the destination address?

By using a service called DNS

How does text compression work?

Data compression is a process in which the size of a file is reduced by re-encoding the file data to use fewer bits of storage than the original file. A fundamental component of data compression is that the original file can be transferred or stored, recreated, and then used later (with a process called decompression).

What are the various RAID strategies?

Data stripping, data mirroring, parity disk (Hamming code), reed Solomon code

What are ROM, Masked ROM, PROM, EPROM, EEPROM?

Devices use when you are trying to keep data with you that will not be changed often. 1. ROM: general term. 2. Masked ROM: Burned in the factory and the program in loaded on to the masked ROM where you cannot change it. 3. PROM: Programmable and it comes raw from the factor, but you can only program it once. 4. EPROM: Let you program multiple times by raising them using UV rays. 5. EEPROM: Can erase them by the use of an electrical signal where you can program them again.

What file actions does Access Control Verification Module envisage for file sharing?

Different types of operation, read only, write only, r/w only, etc.

What is DMA?

Direct Memory Transfer or Access: A part of memory can be earmarked specifically for data type which is allocated for data transfer and is independent from the use of the processor which frees the CPU and lets the DMA chip control.

How do fixed-length records compare against variable-length records?

Direct access can be very easy with fixed-length but not with variable-length.

What is solid state storage? How does it work and how does it compare against the other media type?

Fowler Nordheim: where you storage the electronics in a floating gate transistor where the one and zero remain the same even when powered done. Advantages: It is fast and smaller in size, no moving parts, needs less amount of power, light weight, and very silent. Disadvantages: When it crashes it doesn't give warning and the data transfer rate can go down over time.

Where is the volume name stored on a hard disk, on a tape, and on a CD?

Hard disk: On the first sector of the outer most track. Tap: Very beginning of tape. CD: Inner most part of the CD.

What are the limitations of direct record organization?

Hashing

What information is contained in File Organization?

How the records are going to be contained within the file.

What are the differences between a hub and a switch?

Hub is dumb and works by broadcast only. Switch is more intelligent and with both broadcast, unicast, and multicast.

What could be modified in a spoofing attack?

IP addresses, phone numbers, email addresses

What are the differences between IPv4, IPv6, and MAC addresses?

IPv4 and IPv6 are found in the network layer and the MAC address goes with the data link layer and identifies the network interface card.

How is a network node identified?

IPv4 which has 32-bits, IPv6 which has 128-bits

What is a collision? When and why does it happen?

If two different parties are using the same line for communication then the line gets destroyed.

How can collisions in wired networks be resolved?

If you use CSMA/CD

What is a DQDB network?

In telecommunication, a distributed-queue dual-bus network is a distributed multi-access network that supports integrated communications using a dual bus and distributed queuing.

What kind of the network is IoT?

Internet of things which is a PAN (personal area network).

What is a token ring network? How does it work?

It is used by generating tokens which are very small packets with information and only the party that has a token can transmit information.

What are the advantages of direct record organization?

Its very easy to implement and is fast. Can add and remove records easily.

What are the different types of files?

JPEG (Joint Photographic Experts Group) PNG (Portable Network Graphics) GIF (Graphics Interchange Format) PDF (Portable Document Format) SVG (Scalable Vector Graphics) MP4 (Moving Picture Experts Group)

What are the major responsibilities of file manager?

The File Manager is a system software responsible for the creation, deletion, modification of the files and managing their access, security and the resources used by them. These functions are performed in collaboration with the Device Manager.

What is the difference between absolute filename and relative filename?

The absolute filename always specifies a particular file. By contrast, relative filenames are not unique descriptors.

What is a protocol stack? Why is it required?

The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the suite is the definition of the communication protocols, and the stack is the software implementation of them.

What is a wireless access point?

This is the point which a wireless enabled device connects to a network

What are the different access control techniques?

Three main types of access control systems are: Discretionary Access Control (DAC), Role Based Access Control (RBAC), and Mandatory Access Control (MAC).

What is routing? How is content routed from source to destination on the Internet?

Try to find the best possible or fastest possible route which uses a technique called store and forward to store packets for a moment and figure out what the best possible route is and forward to the next router.

What are the points of comparison between star, bus, ring, and hybrid network topologies? How do they compare against each other?

- Boils down to the amount of money that you can put into a network where every node is functional. - If the media is broken for bus or ring the entire thing might come to a halt. - A star if a cable is broken only that node is effected and the rest of the network stays fine. - Hybrid will try to get the best points of each topology and try to connect to different networks with different topology. - A tree is a connection of busses.

What are the differences between CD-R and CD-RW?

- CD-Recordable and CD-Read/Write. - CD-R has lands and bits where CD-RW has code of specific materials that will change due to the laser. The heating of the laser with either tighten up the molecules or loosen them. This can either convert a one to a zero or zero to a one.

What are the functions of I/O Channels and Control Units?

- I/O channels are the programmable units and are between the CPU and control unit. - They take care of your devices using synchronization between device feeds and buffering between data transfers between the CPU and devices. - Help using with concurrent processing. Because of these channels the CPU can functions separately from the devices. Control units provide the control signal, receive and provide any signals to control the data receives between the main memory and control units.

What are the points of comparison between a switch, router, bridge, and gateway?

- Switch is something that is local that connects the computers. - A router reaches out and forwards packets to the correct route - A bridge connects networks of the same protocols. - A gateway is used if there are different protocols being used.

Why is network communication serial?

- The cost of the entire embedded system becomes cheap and transmits the information over a long distance. - Serial transfer is used in DCE (Data communication Equipment) devices like a modem.

In how many ways is data compression are possible?

- There are two kinds of compression: Lossless and Lossy. - Lossy compression loses data, while lossless compression keeps all the data. - With lossless compression we don't get rid of any data. Instead, the technique is based on finding smarter ways to encode the data.

How does indexed storage work?

- There is an index that can be referenced to find out where the file is. - You have an index block that holds all the pointer together linking every file. - Every file has one.

How do the different seek time algorithms - FCFS, SSTF, SCAN, LOOK, C-SCAN, and C-LOOK work?

1. FCFS: - FCFS is the simplest of all the Disk Scheduling Algorithms. In FCFS, the requests are addressed in the order they arrive in the disk queue. 2. SSTF: In SSTF (Shortest Seek Time First), requests having shortest seek time are executed first. So, the seek time of every request is calculated in advance in the queue and then they are scheduled according to their calculated seek time. As a result, the request near the disk arm will get executed first. SSTF is certainly an improvement over FCFS as it decreases the average response time and increases the throughput of system. 3. SCAN: In SCAN algorithm the disk arm moves into a particular direction and services the requests coming in its path and after reaching the end of disk, it reverses its direction and again services the request arriving in its path. So, this algorithm works as an elevator and hence also known as elevator algorithm. As a result, the requests at the midrange are serviced more and those arriving behind the disk arm will have to wait. 4. LOOK: It is similar to the SCAN disk scheduling algorithm except for the difference that the disk arm in spite of going to the end of the disk goes only to the last request to be serviced in front of the head and then reverses its direction from there only. Thus it prevents the extra delay which occurred due to unnecessary traversal to the end of the disk. 5. C-SCAN: In SCAN algorithm, the disk arm again scans the path that has been scanned, after reversing its direction. So, it may be possible that too many requests are waiting at the other end or there may be zero or few requests pending at the scanned area. These situations are avoided in CSCAN algorithm in which the disk arm instead of reversing its direction goes to the other end of the disk and starts servicing the requests from there. So, the disk arm moves in a circular fashion and this algorithm is also similar to SCAN algorithm and hence it is known as C-SCAN (Circular SCAN). 6. C-LOOK: As LOOK is similar to SCAN algorithm, in similar way, CLOOK is similar to CSCAN disk scheduling algorithm. In CLOOK, the disk arm in spite of going to the end goes only to the last request to be serviced in front of the head and then from there goes to the other end's last request. Thus, it also prevents the extra delay which occurred due to unnecessary traversal to the end of the disk.

What are the major responsibilities of file management with respect to file access?

1. Keeping track of each file. 2. Using of the policies that determine where & how the files would be stored, in order to efficiently use the available storage and provide access to them. 3. Allocating each file when the user is granted access to them, and recording their use. 4. Deallocating the files when their use in finished and are not needed, and also communicating to others about it's availability which are waiting for it.

What are the similarities and differences between CDs, DVDs, and Blu-Ray optical storage media?

1. Similarities: Laser, lands, and pits. Disk sizes are the same. Single spiraling tracks that starts in the center. 2. Differences: Capacities are different, sizes of lands and pits, different lasers,

How does the OSI protocol stack work? What are the functions of the different layers?

1. The Open Systems Interconnection (OSI) model describes seven layers that computer systems use to communicate over a network.

How many types of file organization are used in magnetic disks? Which are they?

3 different file organization: sequential records, direct records, and index sequential records.

What is antivirus and why is it important?

Antivirus software is designed to detect, prevent and take action against malicious software in your computer, including viruses. Even if you're smart with how you use your computer to avoid coming into contact with a virus, antivirus software is an essential part of a good security strategy.

What is a network node?

Any computer that exists in a network.

Why do some packets get lost?

At times the router might have the queue buffer full so the packets might get lost and mobility. They do not get lost permanently.

How can collisions in wireless networks be resolved?

CSMA/CA

What is CSMA-CD?

CSMA/CD = Carrier Sense Multiple Access with Collision Detection * Avoids 2 devices to transmit at same time.

What are the two ways that file extents work?

Can be link by the storage level or directory level

What is CSMA?

Carrier-sense multiple access is a media access control protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus or a band of the electromagnetic spectrum.

What is CSMA-CA?

Carrier-sense multiple access is a media access control with collision avoidance protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus or a band of the electromagnetic spectrum.

What are the points of comparison between circuit switching and packet switching?

Circuit switching you need to reserve resources before starting connections and nobody will be able to use it. With packet switching any line can have packets from multiple parties from the same point in time.

What are Client-Server and Peer-to-Peer Computing Paradigms? Is there a hybrid paradigm too?

Client server are multiple computers in a network where one is designated as a client where the client computer simple makes requests which are done by a high computer with better resources. Peer-to-Peer computing paradigms are where every party is equal where they share files. Hybrid paradigms which uses both of the previously discussed paradigms. An example of that is chat rooms.

How does noncontiguous storage work?

File can use any available storage space.

What are firewalls and why are they important?

Firewalls provide protection against outside cyber attackers by shielding your computer or network from malicious or unnecessary network traffic. Firewalls can also prevent malicious software from accessing a computer or network via the internet.

What are the different types of networks by geographical distribution?

LAN (Local Area Network): A local area network is a network, which is designed to operate over a very small geographical or physical area such as an office, building, a group of buildings, etc. MAN (Metro Area Network): A Metropolitan Area Network is a bigger version of LAN that uses similar technology as LAN. It spans over a larger geographical area such as a town or an entire city. WAN (Wide Area Network): A Wide Area Network is the largest spread network. It spans over very large-distances such as a country, continent or even the whole globe. Two widely separated computers can be connected very easily using WAN. For Example, the Internet. PAN (Personal Area Network).

What do the different seek time algorithms try to achieve?

Minimize the seek time, arm movement, and response time.

What causes conflict in networks?

Multiple parties try to access resources.

What are the differences between Network OSs and Distributed OSs?

Network: Certain features such as single user system and networkability where the user has the power. Distributed: User are free from knowing everything about the network and because it is distributed you have better control. Nothing is completely dependent on one person or machine which makes it a good example of cooperative management.

What does rotational ordering optimize?

Optimize the total time (or search time) or track/sector.

What are packets? What are the benefits of packetization?

Packetization service in network layer provides an ease of transportation of the data packets. Packetization also eliminates single points of failure in data communication systems. Routers present in the network layer reduce network traffic by creating collision and broadcast domains.

What are ARP, RIP, OSPF, and BGP?

Routing protocols ARP: The Address Resolution Protocol is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite RIP: Routing Information Protocol. RIP is used to synchronize the routing table of all the routers on a network. OSPF: Open Shortest Path First. OSPF is used more than RIP in larger scale networks because it has a more efficient system for communication between routers and because it scales better to larger networks. BGP: Border Gateway Protocol. BGP is widely used across the Internet, but usually externally rather than internally.

What is a Virtual Circuit network?

Something that tries to use a packet switching network in the style of a circuit switching network by creating a dedicated path which all the packets are going to follow.

How does image and sound compression work?

Sound and image is put into samples and the samples are converted to their digital equivalent.

What is a SAN?

Storage Area Network: - Data centers - high end storage solution - Vendor specific and require specialized training to implement and support. - Expensive. - High availability

How is data stored in a CD? What is the structure of this storage?

Storage in a spiral with sectors.

What is optical storage media?

Storage that uses one and zeros such as CDs, DVDs, Blu-Ray, Flopticals, Magneto optical, and are storage in lands and pits.

What are the different types of network media and how are they different from one another?

Twisted-pair cable: Use for telephone communication and can cable ethernet networks. Coaxial cable: Coaxial cable, or coax is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric; many coaxial cables also have a protective outer sheath or jacket. Fiber-optic cable: A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. Wireless

What is the structure of the file system in computers used today and what are its benefits and limitations?

Upside down tree and very good for searching but you might have to go through certain directories to locate a file.

How does a capability list work?

When a process tries to gain access to an object, the operating system can check the appropriate capability list. This arrangement has several drawbacks: If each capability list has an entry for all objects, many entries will indicate that no access is allowed.

Can a stress on ethics education help in fighting against access control attacks?

Yes

Is a subdirectory treated as file?

Yes

What is a network?

a communications, data exchange, and resource-sharing system created by linking two or more computers and establishing standards, or protocols, so that they can work together

What is a volume?

a volume or logical drive is a single accessible storage area with a single file system, typically (though not necessarily) resident on a single partition of a hard disk.

What are the two keywords that define a network?

communication and sharing