Friday, 23 August 2019

Characteristics of Cloud Computing

Characteristics of Cloud Computing



characteristics of a Cloud Computing

  1. On demand self Service.
  2. Broad network access.
  3. Resource pooling.
  4. Rapid elasticity.
  5. Measured service.
Characteristics of Cloud Computing
Characteristics of Cloud Computing
  1. On demand self Service : On demand self services such as email, mobile applications,network or server . Here there is no need of humans to provide these services.
  2. Broad network access : Can be able to access from any of the consumer devices such as Mobile Phone, Tablet, Laptop, Workstation.
  3. Resource pooling : Multiple consumers can use multiple physical and virtual resources dynamically assigned and reassigned according to their demand.
  4. Rapid Elasticity : Computing capabilities can be provided to a consumer  automatically.
  5. Measured Service : which he demand. For example in the case of Data Plans in our mobiles if we want limited plan we can subscribe to only limited plan. If we need unlimited plan we can subscribe to that also. Here we pay what we use for(pay per use).
  6. Multi Tenant architecture : Set of resources provided over the cloud and been accessed by number of users across the organization with set of permissions.

What is Cloud Computing ?

What is Cloud Computing?

Cloud Computing can be defined as delivering computing power( CPU, RAM, Network Speeds, Storage OS software) a service over a network (usually on the internet) rather than physically having the computing resources at the customer location.
Example: AWS, Azure, Google Cloud
 Cloud Computing for Beginners
Let’s learn Cloud computing with an example -
Whenever you travel through a bus or train, you take a ticket for your destination and hold back to your seat till you reach your destination. Likewise other passengers also takes ticket and travel in the same bus with you and it hardly bothers you where they go. When your stop comes you get off the bus thanking the driver. Cloud computing is just like that bus, carrying data and information for different users and allows to use its service with minimal cost.



Why the Name Cloud?

The term “Cloud” came from a network design that was used by network engineers to represent the location of various network devices and there inter-connection.  The shape of this network design was like a cloud.
 Cloud Computing for Beginners

Why Cloud Computing?

With increase in computer and Mobile user’s, data storage has become a priority in all fields. Large and small scale businesses today thrive on their data & they spent a huge amount of money to maintain this data. It requires a strong IT support and a storage hub. Not all businesses can afford high cost of in-house IT infrastructure and back up support services. For them Cloud Computing is a cheaper solution. Perhaps its efficiency in storing data, computation and less maintenance cost has succeeded to attract even bigger businesses as well.
Cloud computing decreases the hardware and software demand from the user’s side. The only thing that user must be able to run is the cloud computing systems interface software, which can be as simple as Web browser, and the Cloud network takes care of the rest. We all have experienced cloud computing at some instant of time, some of the popular cloud services we have used or we are still using are mail services like gmail, hotmail or yahoo etc.
While accessing e-mail service our data is stored on cloud server and not on our computer. The technology and infrastructure behind the cloud is invisible. It is less important whether cloud services are based on HTTP, XML, Ruby, PHP or other specific technologies as far as it is user friendly and functional. An individual user can connect to cloud system from his/her own devices like desktop, laptop or mobile.
Cloud computing harnesses small business effectively having limited resources, it gives small businesses access to the technologies that previously were out of their reach.  Cloud computing helps small businesses to convert their maintenance cost into profit. Let’s see how?
In an in-house IT server, you have to pay a lot of attention and ensure that there are no flaws into the system so that it runs smoothly. And in case of any technical glitch you are completely responsible; it will seek a lot of attention, time and money for repair. Whereas, in cloud computing, the service provider takes the complete responsibility of the complication and the technical faults.

Benefits of Cloud Computing

The potential for cost saving is the major reason of cloud services adoption by many organizations.  Cloud computing gives the freedom to use services as per the requirement and pay only for what you use. Due to cloud computing it has become possible to run IT operations as a outsourced unit without much in-house resources.
Following are the benefits of cloud computing:
  1. Lower IT infrastructure and computer costs for users
  2. Improved performance
  3. Fewer Maintenance issues
  4. Instant software updates
  5. Improved compatibility between Operating systems
  6. Backup and recovery
  7. Performance and Scalability
  8. Increased storage capacity
  9. Increase data safety

Types of Clouds

There are four different cloud models that you can subscribe according to business needs:
 Cloud Computing for Beginners
  1. Private Cloud: Herecomputing resources are deployed for one particular organization.  This method is more used for intra-business interactions.  Where the computing resources can be governed, owned and operated by the same organization.
  2. Community Cloud: Herecomputing resources are provided for a community and organizations. 
  3. Public Cloud: This type of cloud is used usually for B2C (Business to Consumer) type interactions.  Here the computing resource is owned, governed and operated by government, an academic or business organization. 
  4. Hybrid Cloud: This type of cloud can be used for both type of interactions -  B2B (Business to Business) or B2C ( Business to Consumer). This deployment method is called hybrid cloud as the computing resources are bound together by different clouds.

Cloud Computing Services

The three major Cloud Computing Offerings are
  • Software as a Service (SaaS)
  • Platform as a Service (PaaS)
  • Infrastructure as a Service (IaaS)
Different business use some or all of these components according to their requirement.
 Cloud Computing for Beginners

SaaS (Software as a Service)

SaaS or software as a service is a software distribution model in which applications are hosted by a vendor or service provider and made available to customers over a network (internet). SaaS is becoming an increasingly prevalent delivery model as underlying technologies that supports Service Oriented Architecture (SOA) or Web Services. Through internet this service is available to users anywhere in the world. 
 Cloud Computing for Beginners
Traditionaly, software application needed to be purchased upfront &then installed it onto your computer. SaaS users on the other hand, instead of purchasing the software subscribes to it, usually on monthly basisvia internet.
Anyone who needs an access to a particular piece of software can be subscribe as a user, whether it is one or two people or every thousands of employees in a corporation. SaaS is compatible with all internet enabled devices.
Many important tasks like accounting, sales, invoicing and planning all can be performed using SaaS.

PaaS (Platform as a Service)

Platform as a service, is referred as PaaS, it provides a platform and environment to allow developers to build applications and services. This service is hosted in the cloud and accessed by the users via internet.
To understand in a simple terms, let compare this with painting a picture, where you are provided with paint colors, different paint brushes and paper by your school teacher and you just have to draw a beautiful picture using those tools. 
 Cloud Computing for Beginners
PaaS services are constantly updated & new features added. Software developers, web developers and business can benefit from PaaS. It provides platform to support application development. It includes software support and management services, storage, networking, deploying, testing, collaborating, hosting and maintaining applications.

IaaS (Infrastructure as a Service)

IaaS (Infrastructure As A Service) is one of the fundamental service model of cloud computing alongside PaaS( Platform as a Service). It provides access to computing resources in a virtualized environment “the cloud” on internet.  It provides computing infrastructure like virtual server space, network connections, bandwidth, load balancers and IP addresses. The pool of hardware resource is extracted from multiple servers and networks usually distributed across numerous data centers.  This provides redundancy and reliability to IaaS.
 Cloud Computing for Beginners
IaaS(Infrastructure as a service) is a complete package for computing. For small scale businesses who are looking for cutting cost on IT infrastructure, IaaS is one of the solutions. Annually a lot of money is spent in maintenance and buying new components like hard-drives, network connections, external storage device etc. which a business owner could have saved for other expenses by using IaaS.

What is Cloud Computing Architecture?

Let’s have a look into Cloud Computing and see what Cloud Computing is made of. Cloud computing comprises of two components front end and back end.  Front end consist client part of cloud computing system. It comprise of interfaces and applications that are required to access the cloud computing platform.
 Cloud Computing for Beginners
While back end refers to the cloud itself, it comprises of the resources that are required for cloud computing services. It consists of virtual machines, servers, data storage, security mechanism etc. It is under providers control.
Cloud computing distributes the file system that spreads over multiple hard disks and machines. Data is never stored in one place only and in case one unit fails the other will take over automatically. The user disk space is allocated on the distributed file system, while another important component is algorithm for resource allocation. Cloud computing is a strong distributed environment and it heavily depends upon strong algorithm. 

Virtualization and Cloud Computing

The main enabling technology for Cloud Computing is Virtualization. Virtualization is a partitioning of single physical server into multiple logical servers.  Once the physical server is divided, each logical server behaves like a physical server and can run an operating system and applications independently.  Many popular companies’s like VmWare and Microsoft provide virtualization services, where instead of using your personal PC for storage and computation, you use their virtual server. They are fast, cost-effective and less time consuming.
For software developers and testers virtualization comes very handy, as it allows developer to write code that runs in many different environments and more importantly to test that code.
Virtualization is mainly used for three main purposes 1) Network Virtualization 2) Server Virtualization  3) Storage Virtualization
Network Virtualization:  It is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others and each channel is independent of others and can be assigned to a specific server or device in real time.
Storage Virtualization: It is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in storage area networks (SANs).
Server Virtualization: Server virtualization is the masking of server resources like processors, RAM, operating system etc, from server users. The intention of server virtualization is to increase the resource sharing and reduce the burden and complexity of computation from users.
Virtualization is the key to unlock the Cloud system, what makes virtualization so important for the cloud is that it decouples the software from the hardware. For example, PC’s can use virtual memory to borrow extra memory from the hard disk. Usually hard disk has a lot more space than memory. Although virtual disks are slower than real memory, if managed properly the substitution works perfectly. Likewise, there is software which can imitate an entire computer, which means 1 computer can perform the functions equals to 20 computers.

Grid Computing Vs Cloud Computing

When we switch on the fan or any electric device, we are less concern about the power supply from where it comes and how it is generated. The power supply or electricity that we receives at our home travels through a chain of network, which includes power stations, transformers, power lines and transmission stations. These components together make a ‘Power Grid’. Likewise, ‘Grid Computing’ is an infrastructure that links computing resources such as PCs, servers, workstations and storage elements and provides the mechanism required to access them.
 Cloud Computing for Beginners
Grid Computing is a middle ware to co-ordinate disparate IT resources across a network, allowing them to function as whole. It is more often used in scientific research and in universities for educational purpose. For example, a group of architect students working on a different project requires a specific designing tool and a software for designing purpose but only couple of them got access to this designing tool, the problem is how they can make this tool available to rest of the students. To make available for other students they will put this designing tool on campus network, now the grid will connect all these computers in campus network and allow student to use designing tool required for their project from anywhere.
Cloud computing and Grid computing is often confused, though there functions are almost similar there approach for their functionality is different.  Let see how they operate-
                      Cloud Computing
                           Grid Computing
  • Cloud computing works more as a service provider for utilizing computer resource
  • Grid computing uses the available resource and interconnected computer systems to accomplish a common goal
  • Cloud computing is a centralized model
  • Grid computing is a decentralized model, where the computation could occur over many administrative model
  • Cloud is a collection of computers usually owned by a single party.
  •  
  • A grid is a collection of computers which is owned by a multiple parties in multiple locations and connected together so that users can share the combined power of resources
  • Cloud offers more services all most all the services like web hosting, DB (Data Base) support and much more
  • Grid provides limited services
  • Cloud computing is typically provided within a single organization (eg : Amazon)
  • Grid computing federates the resources located within different organization.

Utility Computing Vs Cloud Computing

In our previous conversation in “Grid Computing” we have seen how electricity is supplied to our house, also we do know that to keep electricity supply we have to pay the bill. Utility Computing is just like that, we use electricity at home as per our requirement and pay the bill accordingly likewise you will use the services for the computing and pay as per the use this is known as ‘Utility computing’. Utility computing is a good source for small scale usage, it can be done in any server environment and requires Cloud Computing.
 Cloud Computing for Beginners
Utility computing is the process of providing service through an on-demand, pay per use billing method.  The customer or client has access to a virtually unlimited supply of computing solutions over a virtual private network or over the internet, which can be sourced and used whenever it’s required.  Based on the concept of utility computing , grid computing, cloud computing and managed IT services are based.
Through utility computing small businesses with limited budget can easily use software like CRM (Customer Relationship Management) without investing heavily on infrastructure to maintain their clientele base.
                       Utility Computing
                         Cloud Computing
  • Utility computing refers to the ability to charge the offered services, and charge customers for exact usage
  • Cloud Computing also works like utility computing, you pay only for what you use but Cloud Computing might be cheaper, as such, Cloud based app can be up and running in days or weeks.
  • Utility computing users want to be in control of the geographical location of the infrastructure
  • In cloud computing, provider is in complete control of cloud computing services and infrastructure
  • Utility computing is more favorable when performance and selection infrastructure is critical
  • Cloud computing is great and easy to use when the selection infrastructure and performance is not critical
  • Utility computing is a good choice for less resource demanding
  • Cloud computing is a good choice for high resource demanding
  • Utility computing refers to a business model
  • Cloud computing refers to the underlying IT architecture

Security concerns for Cloud Computing

While using cloud computing, the major issue that concerns the users is about its security. 
One concern is that cloud providers themselves may have access to customer’s unencrypted data- whether it’s on disk, in memory or transmitted over the network. 
 Cloud Computing for Beginners
Some countries government may decide to search through data without necessarily notifying the data owner, depending on where the data resides, which is not appreciated and is considered as a privacy breach (Example Prism Program by USA).
To provide security for systems, networks and data cloud computing service providers have joined hands with TCG ( Trusted Computing Group) which is non-profit organization which regularly releases a set of specifications to secure hardware, create self-encrypting drives and improve network security.  It protects the data from root kits and malware. 
As computing has expanded to different devices like hard disk drives and mobile phones, TCG has extended the security measures to include these devices. It provides ability to create a unified data protection policy across all clouds.
Some of the trusted cloud services are Amazon, Box.net, Gmail and many others.

Privacy Concern & Cloud Computing

Privacy present a strong barrier for users to adapt into Cloud Computing systems
There are certain measures which can improve privacy in cloud computing.
  1. The administrative staff of the cloud computing service could theoretically monitor the data moving in memory before it is stored in disk.To keep the confidentiality of a data, administrative and legal controls should prevent this from happening.
  2. The other way for increasing the privacy is to keep the data encrypted at the cloud storage site, preventing unauthorized access through the internet; even cloud vendor can’t access the data either.

Case-Study of Cloud Computing- Royal Mail

  • Subject of Case-Study:Using Cloud Computing for effective communication among staff.
  • Reason for using Cloud Computing:Reducing the cost made after communication for 28,000 employees and to provide advance features and interface of e-mail services to their employees.
Royal mail group, a postal service in U.K, is the only government organization in U.K that serves over 24 million customers through its 12000 post offices and 3000 separate processing sites.  Its logistics systems and parcel-force worldwide handles around 404 million parcel a year. And to do this they need an effective communicative medium. They have recognized the advantage of Cloud Computing and implemented it to their system. It has shown an outstanding performance in inter-communication.
Before moving on to Cloud system, the organization was struggling with the out-of-date software, and due to which the operational efficiency was getting compromised.  As soon as the organization switched on to Cloud System, 28000 employees were supplied with their new collaboration suite, giving them access to tools such as instant messaging and presence awareness.  The employees got more storage place than on local server. The employees became much more productive.
Looking to the success of Cloud Computing in e-mail services and communication .The second strategic move of Royal Mail Group, was to migrating from physical servers to virtual servers, upto 400 servers to create a private cloud based on Microsoft hyper V. This would give a fresh look and additional space to their employees desktop and also provides latest modern exchange environment.
The hyper V project by RMG’s (Royal Mail Group) is estimated to save around 1.8 million pound for them in future and will increase the efficiency of the organization’s internal IT system.

Wednesday, 17 July 2019

Top 35 Linux Interview Questions And Answers

Popular Linux Interview Questions With Answer

The redhat linux interview questions and answers for experienced and fresher are vital for the people who decide to start a career in the Linux. With the help of below-given question, you can ready for the Linux interview and get a job in a top company with a high salary –
1. Explain About Linux
Linux is one of the open source UNIX operating system (OS). It is open source and completely free. It is developed from scratch by the Linus Trovald. This platform is a completely different operating system. It has few distributions such as Fedora, Ubuntu, and others. Linux is everywhere from television, smartwatch, laptop, Smartphone and much more.
2. How Many Types Of Processes In Linux?

There are two types of processes in Linux such as background processes and foreground processes. The background process runs on the Linux background. The users can execute the commands before the Linux background process get completed fully. After the command, the users add an & symbol that make it a background process. The Foreground process while started by the developers run in the foreground. The developers need to wait for few minutes to get executed before providing other commands. Linux interview questions

3. Why Should You Use Linux?

Nowadays, Linux is mostly used for its performance and it is totally different from other OS in the market. It comes with additional features that allow the users to complete the task quickly. It supports different file system and highly secured. Linux is open source OS where the developers gain huge benefits of developing their own custom operating system. It has controllable problems with the malware, virus, and others. The software licensing needed to install Linux is free. These are the main reason for using Linux.

4. What Are Swap Space And Its Benefits?

Swap space is the amount of hard-disk storage or physical memory. It is utilized when the system requires large memory space but the storage of the system is full. The swap space is provided for use by the Linux that allow running the programs temporarily. It occurs when the RAM does not have enough storage space to support the running programs. The memory management involves the memory swapping from as well as to physical storage. The inactive memory space is moved to the swap spaces that free RAM storage. There are various types of tools and commands to manage the usage of swap space.

5. What is Linux used for?

However, Linux is used for carrying out big iron systems such as mainframe computers, and the only OS used on TOP 500 super computers. It is now gradually eliminated in all competitors. It is operated on servers and carry high end performances.

6. Explain Important Features Of Linux OS

Linux has excellent features that provide you best experience. Here you can get the key features of the Linux operating system. 

(1)Linux distros offer live USB or CD for installation. 

(2) Linux offers high-security service in different methods such as Encryption, Authentication, and authorization. 

(3) It offers the hierarchical file system and Linux code is completely free to all. 

(4) You can install Linux kernel as well as an application program on any hardware platform. 

(5) Linux has unique application support and customized keyboards. 

(6) This platform allows different users to use the same device like an application program, memory and hard disk with the various terminals for operation. 

7. Explain About Linux Shell

The Linux shell is a user interface that used for executing the communication and commands with the Linux OS. The shell commands can be classified into two types such as external commands and built-in shell commands. There is a lot of the shell available with the Linux that includes TCSH, BASH, KSH, and CSH.

8. What Is A Virtual Desktop

On the current PC, when there are lots of the windows available and appears maximizing as well as minimizing the window their virtual desktop server as an option. The virtual desktop allows users to open more than one program without any error. It is stored on the remote server and it has few benefits such as lower compatibility problems, enhanced data integrity, resource are used effectively, centralized administration, and others.

9. What Are The Uses of Linux?

It is similar to the other operating systems that can be used for windows, OS X and iOS. This includes lots of configurations that are capable for updating with enough features. It let them focus on operating systems such as word processing applications and linux equivalents. It is accustomed to using other operating systems.

10. What Can You Actually Do With Linux?

There are lots of email applications are carried out in Linux operating system. It includes three most common features which are widely used to come in mind with right flow. This includes Mozilla Thunderbird, Kmail, and others. So, it let the users grab attention on best linux operating systems for varied purposes.

11. How Linux will be Utilized?

Like windows and apple operating system, the Linux is also one of the top notch operating system. To update the extraordinary features, here enormous number of configuration will be included. This process will permit to concentrate on the major operating systems like Linux equivalents and word processing applications in an effective manner.

12. How The Linux Will Work?

In general, in Linux, there are enormous number of email applications have been used. Those email applications will provide certain basic features that can able to used in the perfect manner. This will include various applications such as Kmail, Mozilla Thunderbird and much more. Linux OS will never get affected with virus.

13. What is a Right Typical Size For A Swap Partition Below Linux System?

The suitable size for a swap partition is twice the total amount of the present physical memory found over the system. It is not applicable to minimum size must be the same as the total amount of the memory installed over it. Hope it is helpful to store the right amount in a fine manner.

14. How will Find Out How Much Memory Linux is Using?

In a command shell, it makes use of concatenating command: cat/proc/memento for all memory usage data. Then it would see a right light begin something such as Mm: 64655360. It is complete know as the Linux thinks is found to use with more comfort at all time.

15. How Will Change Permissions Under Linux?

Think that you are systems administer and owner of file or directory, you can grant permission using the chmod command. It is used +symbols to make permission to deny permission. With any of the following letters such as g (group) o (other) and much more. Here the command chmod go+ rw FIlE1.TXT grant read and obtain the file.

16. What is OS?
OS (operating system) is used to provide platform to run our application and software.

17. What is kernel?
Kernel is a core part of any Operating system, which is used to interact hardware with software.
Linux Commands & Technical Interview Questions 2019
Here are few linux commands and technical interview questions:
18. How will you check your kernel version?
uname –a : is a command to check kernel version of your Linux OS.
19. How will you check your memory in Linux?
cat /Proc/meminfo :
Or 
free –m:
20. How will you change your terminal through command?
chvt terminal no
21. How will you check your system hardware in Linux?
cat /proc/cpuinfo
Or 
lscpu
cat /proc/meminfo
Or 
Free –m
cat /proc/partitions
Or 
fdisk –l
22. What is shell?
Shell is a user interface between user and Operating System.

23. How many shells used by Linux?
Many shells are used
less /etc/shells
ksh, sh, csh, tcsh,zsh
Cat /etc/shell
24. How will you list all file in directory, Including The Hidden?
ls –al:- this command will show you all file and directory including the hidden into your present working directory.
25. What is the port no. of ssh?
Default port no of ssh is 22.
26. What Is the port no of telnet?
Default port no of ssh is 23.
27. What is the difference between ssh and telnet?
Both for use remote login on system but ssh is more secure than telnet.
28. How will you check all installed packages of ftp?
rpm –qa | grep ftp
29. What are the contents of /boot?
/boot: – It contains Grub (boot loader of Linux) kernel (the core part of OS) and booting related files.
30. What are the contents of /sbin?
/sbin: – It contain all system command or super user command /usr/sbin.
31. What are the contents of /etc?
/etc: – It contain all configuration file and directory used for server.
32. What are the contents of /dev?
/dev :- It is a location of the devices file.
33. What are the contents of /bin?
/bin :- It contain all executable files or command or user command. /usr/bin also contain user command.
34. What is redirection?

Redirection is standard Input/output of the command, which used to displays on the terminal can be redirected into a file. 
Common redirection operator
> : command > file : this command will redirect output of command into file
>> : command >> file : this command will append output of command into file
< : command < file : this command will receive input from file
2> : command2 > file : this command will redirect error of command into file
2>> : command2 >> file : this command will append error of command into file
&> : Command &> file : this command will redirect output + error of command to file
&>>: Command &>> file : this command will append output + error of command to file 
35. What is Aliases?
Aliases are a short name for large commands.
Alias h=history
For permanent entry of alias in .bashrc file
Type:
vim .bashrc
alias h=history
save and exit
For test your change by logging out, logging back and type
h.