Hi friends, let’s discuss the important concept of Data Mining and the four common tasks of data mining: Data Clustering, Data classification, regression and association rule learning.
This is an important topic to learn and adopt as a career option these days. Lots of people are trying their luck in this field by mastering the data analysis skills. It is a growing field and by 2020 the vacancy graph for professional data analyst, business analyst and data scientist will be at par.
Hope you guys have checked my previous post on Malicious Programs/Malwares for answering the questions related to this section.
Future Scope of Data Analyst:
Apart from future perspective, data mining is an important topic considering the various government exam vacancies for computer science professionals. So, I have tried to collect every important part of topic data mining in this blog.
If you guys want any other topic to be covered, please let me know by adding a comment. Now let’s first understand what Data mining and data analysis is.
What is Data Mining and the use of Data Mining?
Data mining is the process of extracting patterns from data. It is an important tool used by modern business to drive information from data. Data mining is currently used in marketing, profiling, fraud detection and scientific discovery etc.
Tasks of Data Mining:
- Data Clustering: It is the task of discovering groups and structures in the data that are similar in some way. Data clustering is performed without using known structures in data.
- Data Classification: Data classification is the task of generalizing known structures to apply to new data. Common algorithms related to data classifications are: 1.1. Decision tree learning
1.2. Nearest neighbor
1.3. Naïve Bayesian classification
1.4. Neural networks
1.5. Support Vector Machines
3. Regression: With Regression we attempt to find a function which models the data with the least error. There are different strategies related to regression models.
4. Association Rule learning: This learning is used to search for relationships between variables. I would like to share a big example of association rule learning:
With the help of association rule learning, Amazon displays the items frequently bought together to show as a recommendation. Thus helps the customers and increase its sales.
Approaches to Data Mining Problems:
- Discovery of sequential patterns
- Discovery of patterns in time series
- Discovery of classification rules
- Neural Networks
- Generic Algorithms
- Clustering and Segmentation
Goals of Data Mining and Knowledge Discovery:
- Prediction: Data mining can show how certain attributes within the data will behave in future.
- Identification: Data mining can be used to identify the existence of an item
- Classification: Data mining can partition the data so that different classes or categories can be identified
- Optimization: Data mining can be used to optimize the use of limited resources such as time, space, money or materials to optimize the output
What is OLTP (Online Transaction Processing)?
In order to understand OLTP, it is very important to be aware about Transaction and transaction system. So, what is a transaction? What are the properties of transaction system? Let’s analyze the theory of transactions and then we will cover OLTP.
Transaction and Transaction System:
A transaction is nothing but an interaction between different users or different systems or between a user and a system.
Transaction systems: Every organization needs some on-line application system to handle their day to day activities. Some examples of transaction systems are: Salary Processing Library, banking, airline etc.
Every transaction follows the ACID property. Learn it like this. This is an important section and government exams choose multiple questions from this section.
Atomicity: This means a transaction should either completely succeeded or completely fail.
Consistency: Transaction must preserve the database stability. A transaction must transform the database from one consistent state to another
Isolation: This simply means transaction of one user should not interfere with the transactions of some other user in the database.
Durability: Once a transaction is complete means committed, it should be permanently written to the database. This change should be available to all the transactions followed by it.
I hope the ACID properties are clear to you guys. Please let me know if you need more information on this with examples.
Ever wondered how multiple transaction of different users can be processed simultaneously?? If yes check the below magic:
Concurrency: Currency allows two different independent processes to run simultaneously and thus creates parallelism. This is the thing that utilizes the use of fast processing time of computers.
What is Deadlock?
Deadlock is a situation where one transaction is waiting for another transaction to release the resource it needs and vice versa. Therefore, it becomes the case of wait and bound situation and the system halts. Each transaction will be waiting forever for the other to release the resource.
How to prevent Deadlock?
The simple rule to avoid deadlock is if deadlock occurs, one of the participating transaction must be rolled back to allow the other to proceed. So, this way transactions can be performed. There are different kinds of schemes available to decide which transaction should be rolled back.
This decision depends on multiple factors given as following:
- The run time of the transaction.
- Data already updated by the transaction
- Data remaining to be updated by the transaction system
I have tried to cover this section completely friends. Learn these concepts about data science and you will be able to solve each and every question that is related to the data mining section.
In order to master this section, please check my next post of the Previous Year questions of Data Mining section.
Not sure about Computer Networking concepts? Need to score good marks in Computer network section? If yes, do read my next post on Computer Network and Network Topologies. Till then, C yaa friends 🙂
Hi friends, today I am writing about malicious programs – Virus, Root kit, Trojan horse etc and the types of viruses. So, firstly it is very important to know What is malware? It is an important topic for exams like IBPS IT officer, Assistant Manager (IT), SBI IT officer, GIC Officer Scale – I, Computer Teacher, Computer Engineer or any other computer engineer related post. Looking over the importance of this topic, I am explaining this in detail and will also share a questionnaire on it soon. So stay updated with this website and let me know if you want more on this topic. Let’s first understand what Malicious Program is.
What is Malicious Program/Malwares?
Malicious software, which are commonly known as Malwares are a type of software that can harm your computer system. These programs come in different forms for example: viruses, trojans, worms, spyware, adware, root kit, zombie, key loggers etc.
These programs can delete documents, modify or steal the protected data and also add software to your computer programs which are not approved by user.
Hope you get a basic idea of the dangerous nature of these programs. Now, let’s move to the core concepts of this Malicious Programs section so that IT officer post or any computer science post people can answer the questions related to malicious programs.
Types and Forms of Malicious Programs
|Forms of Malicious Programs|
|Type/Form of Malicious Program||Description|
|Virus||It attaches itself to a program and propagates copies of itself to other programs and thus harm the data.|
|Worm||It is a program that propagates copies of itself to other computers basically through Network|
|Trojan Horse||It is a program that contains unexpected additional functionality|
|Backdoor (Trapdoor)||Program that allows unauthorized access to programs and functionality|
|Logic Bomb||It triggers action when a specific condition occurs|
|Exploits||It is a code specific to a single vulnerability or set of vulnerability|
|Auto-rooter||Malicious hacker tools which are used to break into new machines remotely|
|Downloader’s||Usually downloader’s are sent in an email. It is a program that installs other items on a machine that is under attack.|
|Key Loggers||It captures keystrokes on a compromised system. Think a program is stealing your credentials details during a transaction|
|Zombie||Program activated on an infected machine that is activated to launch attacks on other machines|
|Root Kit||These are Set of hacker tools used after attacker has broken into a computer system and gained root-level access|
|Flooders||Flooders are used to attack networked computer systems with large volume of traffic to carry out a denial of service attach (DoS) attack.|
|Spammer Programs||Spammer programs are also a kind of malicious software. These are used to send large volumes of unwanted emails|
|Kit (Virus Generators)||Kit is a set of tools for generating new viruses automatically|
I have tried to provide the maximum information that covers most of the questions from Malicious Programs section for government exams.
Difference between Computer Virus, Computer Worm, Trojan Horses and Bots
Computer Virus vs Computer Worm :
Computer worms are similar to viruses in the manner that they replicate the functional copies of themselves and can cause the same type of damage. But, still there are some differences in the way these malicious programs cause damage.
In contrast to Viruses, which require the spreading of an infected host file, worms do not require a host file to propagate. Instead, worms are standalone software that do not require any host program or human help to propagate from one computer to another. Now let’s see some basic difference between these malicious programs/malware programs:
Computer viruses attach a copy of itself to files or programs, infecting each computer it comes across as it spreads. It usually spreads through Emails or executable files. Some viruses are very annoying because they slow down your computer, while others can wreak havoc on your system. Viruses usually modifies files or it may sometimes change the location of a file.
Computer Worms also replicate themselves but unlike viruses, these malicious programs do not attach themselves to a program. Instead, these spreads from computer network to network and are extremely dangerous.
These can also damage the servers. Computer worms usually do not infect files. Instead these monetize your computer memory or CPU.
These malicious programs are sneaky ones. Trojan horses hides all sorts of malicious goodies and can harm your computer. These malicious programs may look legitimate software at first glance, but when you install these programs they can delete or modify your files.
Unlike viruses and worms, Trojan horses do not replicate themselves.
Bots are a type of malicious programs that may have good intent sometimes. These self-replicating malware is designed to retrieve some sorts of information from the infected system. Bots rarely announce their presence. These malicious programs infect networks in a way that escapes immediate notice.
Life Cycle of Virus/ Phases of Virus:
During its lifetime, a typical virus goes through the following four phases:
- Dormant Phase: In this phase, the malicious program Virus is idle. The virus will eventually be activated by some event, such as a date or the presence of another program of file. Not all virus have this stage.
- Propagation Phase: In this phase, the virus places an identical copies of itself into other programs or into certain areas on the disk. Each infected area/program in the computer system will now contain a clone of the malicious program Virus.
- Triggering Phase: In this phase, the virus is activated to perform the intended function. The triggering phase can be caused by a variety of system events like a specific date or exceeding the disk space to a limit.
- Execution Phase: In this phase, the virus perform the intended function. The performed function may be harmless or can damage files or programs of the system.
Nature of Viruses:
Viruses are designed in a way to take advantage of the details and weakness of a particular system. These malicious programs are usually specific to a particular hardware platform or a particular operating system in some cases.
Hope the nature of these malicious programs is clear up to this point.
Types of Virus:
There are numerous types of viruses but I am sharing the most significant types of Virus here. With the enormous growth of technology and available data, the count of virus types is growing. New viruses are being developed and used. So, here is the list of the most common types of viruses:
- Memory-Resident Virus: It lodges in main memory as part of the resident system program. From that point on, the virus infects every program that executes.
- Stealth Virus: This malicious program/malware is explicitly designed to hide itself from any antivirus software. The purpose of the stealth virus is to defeat the virus detection/scan process. To achieve this, the signature of the virus with vary with each replication. The virus may insert superfluous instructions or can also change the order of the independent instruction inside a program.
- Parasitic Virus: This is the most common form of virus. A parasitic virus attaches itself to the executable files and replicates. Thus this virus infects other executable files when the infected executable file is executed.
- Boot Sector Virus: This virus infects the boot record or the master boot record and thus can prove to be very harmful for the system. Infecting the master boot record, this malicious program spreads when the system is booted with the disk containing the concerned virus.
- Polymorphic Virus: This virus mutates itself with every infection, thereby making the detection of the virus impossible.
- Metamorphic Virus: This is similar to polymorphic virus, with one difference that it rewrites itself completely with every infection. Hence, these virus change the detection very difficult. The metamorphic virus may change their behavior as well as appearance.
Phew… finally I was able to frame all the useful information related to malicious program – Network Security section in this post. Please comment below for any feedback or suggestions. For the previous year IBPS IT Officer/SBI IT Officer/Computer Engineer questions on this section please read my next post here.
Hola friends, today I wanted to share the goodness with you all how a stranger girl helped me in need and that invoked my sleeping humanity. I experienced two sides of life on the same day. Saturday was a busy day and I went for an interview in Gurgaon (now known as Gurugram), Haryana. Although, most of the places in Gurgaon are hardly one to two kilometers apart, still one has to bear the expensive auto or taxi fare on their pocket. For a fresher jobseeker, this becomes quite heavy on their pocket where they are bearing the cost of living in a strange city. I also found that moving from one place to another in Gurgaon is costlier than reaching Gurgaon from Delhi ;p
So, I am sharing my first incident of the day. I was on my way to interview venue in an auto when an older couple asked for a ride in the auto (btw I was in a shared auto). The couple wanted to go to a point to which the auto driver refused. Then, they asked for him to drop to the nearby auto spot for their destination. The couple seemed to be very tired of walking. The auto spot was hardly at 5 minutes distance but the auto driver refused to help this older couple and I felt bad for them. Although, there was just I in his big auto but he chose to drive it as an empty cart rather than helping someone. He can easily drop the couple and show his kind nature with a small task of humanity. That insensitive feeling of the auto driver left me in an upset mood with his decision.
Well, when I was done with my interview process. I was looking for the bus stop and when I google it, it showed that the bus stop is around 1.2KM far from my current place. I am someone who likes to walk a lot but that day I was very tired so I started looking for an auto.
In my research to find a good auto for myself which is not too heavy on my pocket, I found none. Most of the autos were asking for a fare of around 80-120rs for a ride of 1.2KM and that wasn’t shocking for me. Then, a girl on a scooty was observing me. She came and asked the auto how much you are charging for this ride. She was stunned and said it won’t take even 30rs to you and offered me a ride on her scooty.
I was quite surprised with such a gesture from a stranger lady. I accepted her offer and sat on his scooty. She asked me where I am going. Then her eagle eyes saw a bus that I should have caught if I was on time. She drove very fast to catch the bus for me and for me this was like a filmy scene, but no this was all for real. In few minutes I was standing in front of the bus and able to catch the bus just because of that stranger lady. I couldn’t thank her in a good way but we passed smile when the bus was leaving and my whole journey was very delightful with this other side of human nature. So, when she came for help, my trust for humanity became alive.
Yes my friends, good people still exist in this world 🙂
Share your own stories if you have helped someone or somebody has helped you in similar way.
Hola friends! I guess you have already read my previous post of JLL Interview rounds for data analyst profile. Check the further JLL Interview round in this blog. So, most of the time there will be one or two technical tests based on your skill set. You’ll be asked to note down the time required to complete the test.
JLL Interview Rounds
There are total three four to five interview rounds. By Interview rounds, here I mean personal interview test and not the technical pen paper tests. The first interview round is with the HR that may be a telephonic one or in person. If you will succeed, there will be some technical tests.
- The Third JLL Interview Round
The third JLL interview round will be most likely with a senior member of the company of head of that department. Since, most of the time the head of the department of JLL are outside doing some business stuff; you’ll be on a telephonic round with them.
2. JLL Interview Questions
The interviewer at each point you will meet are very supportive and give you the details about their company and their work culture. The Senior member of the company/interviewer will ask questions based on your skills and you daily job routine. Try to answer your questions in detail because they want to know each and everything like what kind of responsibilities you are currently holding for the company. Questions will be based on following things:
- Your daily job duties
- What values you have added for the company
- Why do you want to leave your current company
- What are the current tools that you use in your company
- Any improvement plans if you have suggested to your company
- Why JLL
At the end, she will ask if you have any questions for him/her. Always, prepare some questions about the job post you are going for or prepare some questions that can show you have real interest in their company and what to work for them.
The Fourth JLL Interview Round
Once you are done with the third JLL interview round in a good way, you will asked to attend the fourth JLL Interview round with a management/technical head of the company. So, brush up all the technical skills that you have mentioned in your resume. Do not forget to prepare some questions for them. The technical head can ask some tricky questions, give the reply in a confident manner and focus on providing solution to a particular problem rather than focusing on syntax of your programming code.
The Last JLL Interview Round – Discuss Salary 🙂
The last JLL interview round will be more focused on behavioral questions. Discuss salary wisely and grab the job my friend.
Advice: Always prepare some good interview questions for your interviewer.
JLL is a real estate company and soon it will be dealing with new data science tools. So, one of my friend attended the interview of JLL for Python Data scientist. I am discussing here all the JLL Python Interview questions here. But first of all, lets know why JLL.
Why Choose JLL?
JLL(Jones Lang LaSalle) is an American professional services and investment management company specializing in real estate. It values the diversity of its employees and provide them good opportunity growth. Soon, it is targeting to become one customer data science company. So, why not join JLL 🙂
JLL Python Interview Questions and Interview Process
So, there are total four to five rounds if you are going for JLL Python interview. The very first round will be a telephonic one wherein you will be asked about your current company and job role. The interviewer was very supportive in my friends’ case.
The interviewer will explain about the job role and what a JLL python data scientist does in their company. The interviewer will ask simple managerial type questions and you’ll have to provide him/her your scale in a particular skills.
Give Correct ratings for your skills, Interviewer will make a note of it for future rounds.
Further questions will be like what is your notice period and and further date will be intimated to you if the interview finds you a right candidate.
JLL Python Interview Questions and Answers
There will a technical test based on SQL and Python. You”ll find the test is simple if you know your skills :p. The interviewer will also ask you to write on the test how much time did you take to complete the test. It took my friend around 15 mins to complete the SQL test and 25 min to complete the JLL Python Interview questions.
JLL Python Technical Test Question and Answers
The python test questions were based on basic understanding of Python language. The questions include following things:
- Python Lists and Subsetting Lists
- Lembda function in Python
- Self in Python
- Truncating in Python
- Sum of lists
- Sum of arrays
- Data type operations
- Local variable vs dynamic variance concept
Python test is an MCQ level test with questions are around 25-30 wherein either you have to calculate the output of the code or write the answer on your own. So, strengthen your skills.
JLL SQL Test Questions and Answers
The JLL SQL test was very easy for my friend. According to him, the questions were based on the following things:
- Select queries
- SQL Joins
- How to create views
- Selecting a particular output using where clause
- Inner queries
- Inserting values into table
- Trimming values
- Round function of SQL
Find out my next post on further JLL Interview rounds, if you want to grab a job in JLL.
So, here we are discussing all the cons of working in Third Part Payroll system. As you may have already visited my previous post of What is Third Party Payroll System? What are the Pros and Cons of working in Third Party Payroll, now lets check the cons of working in Third Party payroll system in detail:
- Low Salary
You’ll get low salary as compare to the market standards for the same job posts. The reason being, some part of your salary will be taken by the your third party payroll company. So, don’t cry for not getting the actual price value of your work.
2. Not getting Salary on time
Since you will be working on client site, you’ll never know what’s the delay in getting salary when you are already out of budget for the month. Most of time, you won’t get your monthly income on time. So, hell no to the groceries..
3. Rewards are delayed
So if you are someone who likes to work hard and a good performer, forget about your incentives. And, when you will go to your HR, they will say something…there is some internal issue in the accounts section. Incentives requires approval from a long chain of people and at the end you won’t get it…because somebody has already disapproved it. Bear the cons of working in third party payroll system.
4. HR is the God
Your only point of contact at client site will be your HR and that would be of no use many times. HR considers himself/herself the God in such scenario and you won’t know who should be your next point of contact if HR misbehaves with you.
5. Slow Growth and Zero Job Security
The job growth is very slow for the ones who are working in third party payroll system. You will work hard and still won’t get much. At the end, when you are discussing the appraisal the so called God (HR) will explain you about the budget specified by the client for your process. And yes, there is no job security. Just one error and you will get escalation emails from client, then manager and then HR. The quality demand is always very high as compared to your pay. Your soul will be saying I want more at appraisal time.
So, don’t bear the cons of working in third party payroll system. Just prepare for job interviews given on my website and switch the job 🙂
Hola friends 🙂 I am back with another interview experience and this time for PWC. Check out this blog for all PWC interview questions and answers for Hadoop. PWC is a big 4 accounting firm and a very good company to work with. So, I met one of my friend this Sunday and he shared his PWC interview experience with me including all the PWC interview Question and Answers for Hadoop programmers.
PWC Interview Questions and Answers – Test Pattern
The PWC test paper for Hadoop contains multiple sections from Map-reduce program, Hadoop architecture, Unix scripting, SQL queries, Oozie and Sqoop. So, if you are preparing for a big 4 MNC read the following questions and get yourself ready if you are a Hadoop programmer.
Let’s analyze the PWC Interview Questions and Answers for Hadoop section wise:
- Hadoop Architecture:
You must be very much clear about the core concepts of Hadoop architecture to answer the question of this section. The questions will be based upon split count required while saving a file in HDFS against the provided maximum and minimum split size.
Also, this involves questions on the understanding of node manager like what if the name node fails. Also, you would be required to write the whole process when a client submits a request to Hadoop System.
2. Map-Reduce Programming Paradigm
This section contains questions like how many map and reduce tasks will this SQL query takes. Hence, check out such questions and increase your knowledge. There will be a programming questions too wherein you would be asked to write the code in any of the following language: Python/Java/Ruby.
Another question will be how Hadoop allocates Map tasks and reduce tasks.
3. SQL Query Questions
This section contains questions mainly on joins (inner join, outer join, left join etc.) like writing queries for the desired join and to tell the count of elements returned in the output. Also, there will be questions where you will be asked to write a query to find out the nth highest or lowest salary of an employee from a given table.
This sections of PWC interview questions and answer set contains questions like how to write a command to send a task in background. Then, again to take that command in foreground and later on how to kill that particular task.
5. Unix Commands
This section will ask you questions like how to print the nth line of a csv file. Also, some commands like print the nth line where condition = “some value”.
6. Sqoop and Oozie
This sections covers questions on the basic understanding of commands needed to transfer data between RDBMS and Hadoop system and also on the inter cluster Hadoop transfer system.
Oozie section contains two questions – one on Oozie workflow configuration and second on the Fork and join parameter.
Hope this article will help future aspirants 🙂 Also, check my next article of Dunnhumby interview questions.
Please share your comments below.
Hi Friends, I have many friends who are currently working on third party payroll system and they shared their experiences with me. Most of my friends who are currently working for third party payroll companies shared the consequences they are dealing with now.
But, firstly let me take you to the pros of working in third party payroll companies and what is third party payroll system:
What is Third Party Payroll System?
Third party payroll system is basically working for a company and getting the salary from some other company. For example, working for an MNC like TCS while getting paid by a consultancy for the same (P.S. it is different from freelancers work). Also, you are not considered an employee of TCS for this. Most of the time, you will be working at client site. Now let’s see some pros of working in Third party payroll system and the companies up for it.
Pros of Working in Third Party Payroll System
- Benefits of Client Company
Since you will be working at client site, so there must be some occasions like festivals when the client company is providing some facilities and goods to its employees. That time, you are also benefited with those goods and services.
2. Learning Opportunities and Challenges
Working on-site, provides ample learning opportunities and challenges. It gives happy experiences to meet new people and work on different kind of tools.
3. Recognition for Good Work
If you do something very good while being on third party payroll system, this can give you a two sided rewards and recognition for it. One from the client side and the other one from the company that is paying you.
Cons of Working in Third Party Payroll System
Phew…I could only found the two pros of working on third party payroll system reviews from my friends but the list of cons is too big..
- Salary is low compared to Market Standards
- Not Getting Salary on Time
- Rewards are delayed
- Small mistakes are considered Big
- Confusion about Point of Contact
- HR is the only God
- Growth is very slow
- Difficulty in Job Switch
- Get used to words like Vendors
- Job Security
- False Promises
- Working on Internal Tools
Let’s discuss all these cons in my next post.
Hi Friends, today I am sharing with you the Python Test pattern of Dunnhumby. Go through the details to know about Dunnhumby Python Analyst Placement Paper pattern, scoring and further interview process. Also, I would share with you all the details on which you need to focus to get selected as a Dunnhumby Analyst. One of my friend appeared for the Analyst profile for Dunnhumby, Gurgaon location. The interview process started early at 9:00 AM.
Dunnhumby is a customer science company and values the candidates that understand the value that the company adds to its customers. Getting a job at Dunnhumby is like being in your good luck. So, there were many candidates that were either going to appear for an interview on R or Python. My friend appeared for a test on Python. So, Here is the structure of the Python test:
Dunnhumby Placement Paper Pattern
The Dunnhumby Python test contains a total of 15 questions. Out of these 15 questions, 4 were objective questions while 11 of these questions were coding questions where you are supposed to write the answers. Most of these questions were of different scores (2 marks to 5 marks). The questions were typically based on the following things :
Dunnhumby Placement Paper Pattern (Analyst) – Python
- Understanding of Python lists
- Understanding of operators and float values
- For loop applied on lists
- Reading the CSV files (few tables were provided and you need to write code to store these files as data frames)
- Write the code to change the data type of a column into some other
- Write the code to shuffle the list values in a significant way
- Sort the table values based on a specific column (ascending or descending order)
- Select a particular column based on column joins from two tables
- Select column values and calculate min, max, average, count, sum
- Re-sampling the data of tables
Dunnhumby Python Objective Test Paper Scoring
In the python technical objective questions you have to choose the output of the applied functions, operators. For this, one should have proper understanding of lists and loops and object referencing. Each objective question contains multiple sub-questions with different score weightage.
The second round will be a case study round and subsequent questions based on it. First of all, do review the already available case studies present on the official website of Dunnhumby. This will help you a lot in forming the logic and giving you an idea of the work Dunnhumby is doing for its clients. As aresult, you will be able to answer the questions asked during this case study interview. Also, wear a smile on your face since nobody likes sad faces :p
That’s all my friends. Best of luck for your interview! 🙂
Please share your interview stories in the comment section. Or you can also share some other company interview experience to me on my contact id.