Notes, abstracts, papers, exams and problems of Computers

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Classified in Computers

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Parte 1

1. What is a resource record?

Resource Records define data types in the Domain Name System (DNS)

2. What is the difference between a recursive and a iterative query in DNS? When is each type of query used?

Recursive DNS queries occur when a DNS client requests Information from a DNS server that is set to query subsequent DNS servers until A definitive answer is returned to the client.

In customer requests and fordwarded

Iterative DNS queries are ones in which a DNS server is Queried and returns an answer without querying other DNS servers

In name servers

3. Some computers are given a different IP address each time They connect to the internet.An internet service provider (ISP) can use a few IP addresses to serve many  customers That way….... Continue reading "Connection" »


Classified in Computers

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A Joystick is another input device you can connect to a computer system. The Joystick is able to move in eight directions. Joysticks are mostly used in computer games to control the way a picture on the screen moves. A Trackerball works to exactly the same way as a mouse, except that the ball is on the top. A Light Pen acan be used to draw pictures directly on to a computer screen or to read the pattern on a barcode. Using a Scanner, you can input printed drawings, photograph or text into a computer


Classified in Computers

Written at on English with a size of 3.64 KB.

types of network: depend on the geographical size

1. LAN local are network: one geographical area, is large, all computers belong to the same organization: allows user to log from any part of the organisation, easy share of data, help manage system, user work together
2. WLAN: wireless lan: connect wirelessly, need special security
3. PAN: personal area network: devices are connected to computer, to transfer data or synchronise devices, by bluetooth or USB
4. WAN and MAN: man (metropolitan area network): large area, series of lans connected. Wan (wide area network): cover larger areas, connect many computers and lans together, uses vpn
5: SAN storage area network: stores data, conatins multiple hard disks. Stored is mantianed in a single location:
... Continue reading "itgs" »


Classified in Computers

Written at on English with a size of 5.17 KB.

Adware is a type of free software supported by advertisements that showup in Pop-up windows or on a toolbar on your computer or browser. Mostadware is Annoying, but safe. But some is used to gather your personal information, track The websites you visit or even record your keystrokes. How to Recognize adware Your device is probably infected with adware if you Start seeing ads popping up in applications where you hadn't seen them before. Pop-ups can also show up on your computer's desktop even when you're not Browsing the Internet. Also, your browser's homepage may have been Changed. How to remove adware Before removing adware from your Device, be sure to back up any important files that you want to keep safe. Then Use antivirus or adware removal... Continue reading "pene" »


Classified in Computers

Written at on English with a size of 2.22 KB.

1.A) f(n) = 10 n^2 log (n^10) + n log (n^5) => o(n^2)    1.B) f(n) = 2^100 n^4 + n^3 => o (n^4)

2.A) 2 nested for inside for =>  n [n+n] = 2n^2

2.B) no. Of primitive operations (1 comparison & 1 return tot=2), 1 for println, (1 for division & 1 for recursive call) => running time is o(n)

2.C) Assignment 1, comparison 1, division 1 & assignment 1 tot=2, addition 1 & assignment 1 tot= 2 (while n), return 1 => running time o(n)

3.A) c2g(n) above f(n) and c1g(n) under f(n)

for constant c1 and no f(n) is omega (g(n)) for every n>=no || for constant c2 and no f(n) is O(g(n)) for every n>=no then f(n) = theta (g(n))

3.B) cg(n) above f(n) >> for constant c and no   f(n)= O(g(n))

3.C) cg(n) under f(n) &... Continue reading "Algorithms" »


Classified in Computers

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What is an array? - An Array is an ordered collection of items. 

What is the following Array -   int[] arr = new int[3]; - One-dimensional array
What is the output of the following Java program? - No output and there is an error when the program is Compiled.

if ((i != j) && (a[i] == a[j])) – -1 when lonely false, works
if (a[i] == a[j]) { - always returns -1 (fails)
if break removed, run slower
2 3  return x + secretMethod(x, n - 1);  -   4
2 3 return x * secretMethod(x, n - 1); -   0
4 return x * secretMethod(x - 2);   -   8
insertion sort, but bubbles all prev for each element
Selection sort – find next smallest and swap into n element. N+1.
Radix sort – buckets. Start with LSB.

5 7         System.Out.Println(node.
... Continue reading "Radix" »


Classified in Computers

Written at on English with a size of 6.12 KB.

Introducing networks

A network is created when more than one device is connected together. A network can be a small collection of computers connected within a building (eg a school, business or home) or it can be a wide collection of computers connected around the world.


-Communication – it is easy (and often free) to communicate using email, text messages, voice calls and video calls.

-Roaming – if information is stored on a network, it means users are not fixed to one place. They can use computers anywhere in the world to access their information.

-Sharing information – it is easy to share files and information over a network. Music and video files, for instance, can be stored on one device and shared across many computers, so

... Continue reading "fkgfk" »

Hardware y software

Classified in Computers

Written at on English with a size of 4.23 KB.

Hardware: physical equipment used to process, store or transmit computer programs or data.

CPU: element that controls and executes the operations that take place inside the computer in order to carry out the automatic treatment of information.
CU (control unit): coordinates all the activities and elements of the computer, and a set of records, which are little storage spaces where the information that the CPU manages is temporarily stored.
ALU (arithmetic and logic unit): performs basic operations over data.
Memory: bits’ storehouse where all programs and all data are saved.
Random access memory: performs reading and writing operations, and allows to access random memory positions.
Read only memory: just allows reading operations and it contains
... Continue reading "Hardware y software" »

Computer science

Classified in Computers

Written at on English with a size of 5.79 KB.

public class TrainList<X>
    Node<X> first;
    Node<X> last;
    public void add(X value)
    public void addFirst(X value)
        Node<X> x = new Node<X>(value);
        if(first == null)
            last = x;
            x.Next = first;
        first = x;
    public void addLast(X value)
       Node<X> x = new Node<X>(value);
       if(first == null)
           first = x;
            last.Next = x;
       last = x;
    public int size()
... Continue reading "Computer science" »

Constants pi type p decimals 2 value '3.1'

Classified in Computers

Written at on English with a size of 4.81 KB.

Module 3 Quiz

1.Structured Query Language (SQL) is considered a procedural language. False
2.PL/SQL fully supports SQL data types. True
3. The term anonymous blocks refers to blocks of code that are not stored for reuse and do not exist after being executed. True
4.The BEGIN section of a PL/SQL block contains code that creates variables, cursors, and types. True
5. Assignment statements are used to put or change the values of variables. True
6. A disadvantage of using the %TYPE attribute is that there is a slight performance hit in that the database server must look up the data type from the data dictionary. True
7. A collection is a data type that can store multiple values of different data types as one unit. False
8. A scalar variable can hold multiple... Continue reading "Constants pi type p decimals 2 value '3.1'" »