Tuesday, 31 January 2017

Explain what happens with React's "virtual DOM" whenever render fires, and why it's so great.

Whenever React renders the component tree, it looks for changes from the virtual DOM to the actual DOM. If there are changes, it will update only the affected nodes in the most efficient way. If there are no changes, it doesn't even touch the webpage.
This is great because Javascript is so fast, but the DOM is so slow. Whenever we have to actually go to the DOM and update elements, that's the slow part of any webpage. By having a virtual DOM where everything is updated behind the scenes and only changed in the actual DOM if there's differences, it allows our applications to become super fast.

What are Synthetic events?

In order to ensure events have consistent properties across different browsers, React wraps the browser's native events into "synthetic events", consolidating browser behaviors into one API. Synthetic events are a cross-browser wrapper around the browser's native event system.

How you will update a Component's state?

We update state by calling this.setState(), this causes our component to re-render.

this.setState({showComments:true})
Will only update the properties an argument, not replace the entire state object.
How is state available, and what is it by default?
this.state == null

What is a state? How to use state?

State handles data changes. State is a JavaScript object that lives inside each component. We can access it via this.state. In React we modify the DOM indirectly, by updating each component's state and letting React handle updates to the DOM.
The state is a vital part of React apps, making user interfaces interactive. Represents data that changes over time.
We declare an initial state in the component's constructor. As first line call the super function. (To communicate with other components). In order to create the initial state for a component, we must declare the property this.state as an object in the class constructor function.
We update state by calling this.setState(), this causes our component to re-render.

Why do we capitalize components?

Because they're a constructor. It is not a rendered DOM element YET, it just has the capacity to render out a DOM element whenever we print it (with something like <Header />).

What is virtual DOM diffing?

When Component rendering for the second time Virtual DOM checks what element get changed and print the changed element to the page, other elements remain untouched.
The Virtual DOM diffing allows React to minimize changes to the DOM as a result of user actions, therefore increasing browser performance. This is why it's fast!

How Virtual DOM Works?

When you render a JSX element, every single virtual DOM object gets updated.This sounds incredibly inefficient, but the cost is insignificant because the virtual DOM can update so quickly. Once the virtual DOM has updated, then React compares the virtual DOM with a virtual DOM snapshot that was taken right before the update.
By comparing the new virtual DOM with a pre-update version, React figures out exactly which virtual DOM objects have changed. This process is called "diffing."
Once React knows which virtual DOM objects have changed, then React updates those objects, and only those objects, on the real DOM.

Explain Virtual DOM?

In React, for every DOM object, there is a corresponding "virtual DOM object." A virtual DOM object is a representation of a DOM object, like a lightweight copy. Think of manipulating the virtual DOM as editing a blueprint, as opposed to moving rooms in an actual house.

Explain what is Prop?

When we use our defined components, we can add attributes called props. These attributes are available in our component as this.props and can be used in our render method to render dynamic data.
var MyComponent = React.createClass({
    render: function(){
        return (
            <h1>Hello, {this.props.name}!</h1>
        );
    }
});

In JSX why you can't use "class" word?

In JSX, you can't use the word class. You have to use className instead because JSX gets translated into JavaScript, and class is a reserved word in JavaScript.

A JSX expression must have exactly how many outermost elements?

It must have exactly one outermost element.
var paragraphs = (
<div id="i-am-the-outermost-element">
<p>I am a paragraph.</p>
<p>I, too, am a paragraph.</p>
</div>
);

But this code will not work:
var paragraphs = (
<p>I am a paragraph.</p>
<p>I, too, am a paragraph.</p>
);
The first opening tag and the final closing tag of a JSX expression must belong to the same JSX element!

Can Browsers read JSX? If not, Why?

JSX is not valid JavaScript. Web browsers can't read it! If a JavaScript file contains JSX code, then that file will have to be compiled. That means that before the file reaches a web browser, a JSX compiler will translate any JSX into regular JavaScript.

What do you understand by JSX? Explain it.

JSX is a syntax extension for JavaScript. Basically HTML that goes into a js file to be compiled into real HTML. A JSX expression must have exactly one outermost element. Every JSX element is secretly a call to React.createElement().
Example: var h1 = <h1>Hello, World!</h1>

Examples of JSX elements with the attributes:
<a href="http://www.yahoo.com">Welcome to the Yahoo</a>;
var title = <h1 id="title">Introduction to React.js: Part I</h1>;

An example of a nested JSX expression being saved as a variable:
var theFacebook = (
<a href="https://www.facebook.com">
<h1>
Click me
</h1>
</a>
);

*If a JSX expression takes up more than one line, then you should wrap the multi-line JSX expression in parentheses.

What are the advantages/benefits and limitations of React?

Following are the advantages/benefits and limitations of React
Advantages/benefits:
  • ReactJS can be used on client and server side too.
  • ReactJS components are highly re-usable. 
  • React comes with a small API. Beginners will find it easy to learn and start using it.
  • ReactJS uses virtual DOM which is JavaScript object. This will improve apps performance since JavaScript virtual DOM is faster than the regular DOM.
  • Component and Data patterns improve readability which helps to maintain larger apps.
  • ReactJS can be used with other frameworks(Backbone.js, Angular.js) as it is only a view layer..
React Limitations:
  • React only covers view layer of the app so you still need to choose other technologies to get a complete tooling set for development.
  • React is using inline templating and JSX. This can seem awkward to some developers.
  • React library is too large.

What is ReactJS?

React.js is a JavaScript library developed by engineers at Facebook for building user interfaces. ReactJS allows us to create reusable UI components. It is currently one of the most popular JavaScript libraries and it has strong foundation and large community behind it.

What are the benefits of Animated Data Transitions?


  • Improves perception of changes between statistical data graphics
  • Helps tell the story of data changes through time in a meaningful way
  • Improves user interaction and understanding
  • Enhances visual presentation and communication of the cause-and-effect relationships

What is the difference between Dundas Dashboard and Dundas BI?

Dundas BI is a completely separate product with a different codebase and an expanded scope, focusing on self-serve business intelligence, full API support, ETL, reporting, scorecards, and more. Based on the latest web standards including HTML5, JavaScript and CSS, Dundas BI works and looks the same on a desktop as it does on a mobile device such as a tablet or smartphone.

Explain the Key Features of Dundas BI?

Following are the Key Features and Benefits of Dundas BI
  • Self-Serve Business Intelligence: Dundas BI gives you the ability to create your own reports, run ad-hoc queries, and perform data analysis, all without having to involve your organization's technical or IT staff. From the interactive designer screen in Dundas BI, you can easily explore available data sources and use intuitive operations to arrange dashboard, report, or scorecard views of your data. For further analysis, you can apply formulas to data using a familiar scripting interface. Smart defaults and automatic data preparation are used throughout Dundas BI to provide a streamlined workflow, which means there are a lot fewer steps needed to progress from your data to desired visuals.
  • Full API Support: Right from the start, we focused our development of Dundas BI on extensibility and integration. Every capability you see visually in the user interface of Dundas BI is powered by underlying APIs which you have access to as well. Dundas BI conveniently offers .NET, REST, and JavaScript APIs. Depending on the type of extension, integration, or embedding you require, a combination of these public APIs may be used. In particular, our REST API makes it possible to access available functionality regardless of the programming language, platform, or operating system you are using.
  • HTML5, Mobile & Touch: The client-side of the Dundas BI platform is based entirely on the latest web standards including HTML5, JavaScript, and CSS. There is no requirement for Silverlight or other browser plug-ins. This means Dundas BI works and looks the same on a desktop as it does on a mobile device such as a tablet or smartphone. The user interface of Dundas BI fully supports touch-based gestures so you can even design dashboards and reports directly on an iPad. All you need is a standards-compliant browser for your specific client device.
  • Data Visualizations: Dundas BI provides an array of data visualization types you can use to compose your dashboard and report views. Our JavaScript-based data controls including charts, maps, tables, gauges and more, have all been designed with performance and support for ad-hoc analysis in mind. We've also programmed our data controls with default styles and behavior that conform to established best practices in data visualization.
  • ETL Layer & In-Memory Analytics: Extract-Transform-Load (ETL) capability is built directly into Dundas BI via our data cube layer. Simply add transform nodes to a data cube and connect them together to perform data cleansing or join tables sourced from different databases. The output of a data cube can be cached to our internal data warehouse for improved performance. Or, you can build an in-memory analytical model of your data to enable even faster results for analytical queries.
  • Administration & Configuration: Dundas BI provides a flexible data security model which includes support for multi-tenant / SaaS deployment. For scalability, load balancing is supported through the use of application and data processing server groups. Application configuration can also be performed in Dundas BI without having to log in directly on the server, making it easier to administer the system and perform tasks such as changing configuration settings or adding a new license.


Explain what is Dundas BI?

Dundas BI is a state-of-the-art business intelligence platform for building and using interactive dashboards, reports, scorecards, and more. You can deploy Dundas BI as the central data portal for your organization, or integrate it into an existing website as part of a custom or embedded BI solution.

Tuesday, 24 January 2017

What is Power BI Desktop?

Power BI Desktop is a free desktop application you can install right on your own computer. Power BI Desktop works cohesively with the Power BI service by providing advanced data exploration, shaping, modeling, and report creation with highly interactive visualizations. You can save your work to a file, and publish your data and reports right to your Power BI site to share with others.

What’s the difference between Power BI and Power BI Pro?

Power BI provides all sorts of features to help you get started exploring data in a whole new way. Power BI Pro provides all of the same great features in Power BI, plus additional features like more storage capacity, scheduling data refresh more frequent than daily, live data sources with full interactivity, groups, and more. Learn more about the differences between Power BI Pro and the free Power BI.

Top 60 AWS DevOps Real Time Interview Questions Answers

Here we come with most growing technology related interview questions, the technology is known as Amazon Virtual Private Cloud, we are posting this set after got lots of request from our previous article readers( 60 AWS Interview Questions) which become very famous and we got many comments and one guys send thanks email to us because he got selected and he respect our previous article with play big role in his selection.

He has cracked "Adobe Systems" AWS interview and got jobs. We say thanks for such a kind email. :)
After that we have written "95 AWS PVC interview questions" and now come with AWS DevOps set
And we want to get more such emails from you(readers) Best of luck...... pdf will be available soon

AWS DevOps Real Time Interview Questions Answers


  • What is DevOps? AWS DevOps Interview Questions Ans...
  • What are the Advantage/Benefits of DevOps? AWS Dev...
  • What are the Advantage/Benefits of using AWS for D...
  • DevOps focuses on 4 primary areas within IT?
  • What do you understand by below diagram?

  • What are the AWS Services for DevOps?
  • What are the steps to build a custom VPC?
  • What do you understand by Agile Software Developme...
  • How do you practice DevOps?
  • What is Software-as-a-Service?
  • What is Elastic Block Store?
  • What are the Disadvantages of using DevOps?
  • What are the Principles of DevOps?
  • Deploy vs. Release in DevOps? What do you understa...
  • What is Chef?
  • What do you understand by Acceptance Testing?
  • What do you understand by NGINX?
  • What is Dark Launch?
  • What do you understand by term Provisioning in Dev...
  • Explain Git?
  • Explain what do you understand by A3 Problem Solvi...
  • What do you understand by LXC?
  • What is Build Automation?
  • What is Scrum?
  • What is Puppet?
  • Monday, 23 January 2017

    What is Puppet?

    Puppet is a Configuration Management tool that is used for deploying, configuring and managing servers. It performs the following functions:

    • Defining distinct configurations for each and every host, and continuously checking and confirming whether the required configuration is in place and is not altered (if altered Puppet will revert back to the required configuration) on the host.
    • Dynamic scaling-up and scaling-down of machines.
    • Providing control over all your configured machines, so a centralized (master-server or repo-based) change gets propagated to all, automatically.


    What is Scrum?

    Scrum is a simple framework for effective team collaboration on complex projects. Scrum provides a small set of rules that create "just enough" structure for teams to be able to focus their innovation on solving what might otherwise be an insurmountable challenge. (Scrum.org)

    What is Build Automation?

    Tools or frameworks that allow source code to be automatically compiled into releasable binaries. Usually includes code-level unit testing to ensure individual pieces of code behave as expected.

    What do you understand by LXC?

    LXC - (LinuX Container) is an operating system-level virtualization method that allows multiple isolated Linux systems to run as a single host that acts as the controller. Virtualization is not provided through Virtual machines, but rather through a virtual environment with a process set and network space. Each isolated system gets its own directory structure, network devices, IP addresses and process table. It's written in C, Python, Shell and LUA.

    Explain what do you understand by A3 Problem Solving?

    A structured problem‐solving approach that uses a lean tool called the A3 Problem‐Solving Report. The term "A3" represents the paper size historically used for the report (a size roughly equivalent to 11" x 17").

    Explain Git?

    Git is a free, open source distributed version control system tool designed to handle everything from small to very large projects with speed and efficiency. It was created by Linus Torvalds in 2005 to develop Linux Kernel. Git has the functionality, performance, security and flexibility that most teams and individual developers need.

    What do you understand by term Provisioning in DevOps?

    Provisioning is the process of preparing new systems for users (in a Continuous Delivery scenario, typically development or test teams). The systems are generally virtualized and instantiated on demand. Configuration of the machines to install operating systems, middle-ware, etc. is handled by automated system configuration management tools, which also verify that the desired configuration is maintained.

    What is Dark Launch?

    It is a go-live strategy in which code implementing new features is released to a subset of the production environment but is not visibly, or only partially, activated. The code is exercised, however, in a production setting without users being aware of it.

    What do you understand by NGINX?

    NGINX is open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. ... In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers

    What do you understand by Acceptance Testing?

    Acceptance Testing is typically high-level testing of the entire system carried out to determine whether the overall quality of both new and existing features is good enough for the system to go to production.

    What is Chef?

    Chef is an automation tool that provides a way to define infrastructure as code. Infrastructure as code (IAC) simply means that managing infrastructure by writing code (Automating infrastructure) rather than using manual processes. It can also be termed as programmable infrastructure. Chef uses a pure-Ruby, domain-specific language (DSL) for writing system configurations.

    Thursday, 19 January 2017

    What are the Principles of DevOps?


    • Collaboration
    • Breakdown the barriers
    • Work as one team end to end
    • Treat Infrastructure as code
    • Support business and IT agility
    • Automate everything
    • Test everything
    • Measure & monitor everything 

    What are the Disadvantages of using DevOps?

    1. Lack of resources (Developers)
    2. Developer are so costly due to lack of resources
    3. Difficult to hire good DevOps developer.
    4. DevOps requires deep cultural and organizational change. That means changing behavior -- a lot. It means throwing out decades of embedded explicit and implicit practices. You have to tell the veterans accustomed to running things that much of what they know and do every day is obsolete.
    5. The DevOps strategy needs support from the top of the organization to the bottom. The entire executive leadership team -- not just the CIO -- should know why this is important and how to make it a success.

    What is Elastic Block Store?

    Elastic Block Store aka EBS is a type of block storage system that provides persistent block storage volumes for use with EC2.

    What is Software-as-a-Service?

    It is a software distribution model where applications are hosted by a vendor and made available to customers over the Internet

    How do you practice DevOps?

    By using automated testing, continuous integration, continuous delivery and automated infrastructure.

    What are the steps to build a custom VPC?

    Below are the steps of build a custome VPC:

    1. Create a VPC
    2. Create subnets
    3. Create an internet gateway (IGW)
    4. Attach the new IGW to your VPC
    5. Create a new route table (RT)
    6. Add the IGW as a route to the new RT
    7. Add a subnet to the RTs subnet associations (this will be the public facing subnet)
    8. Create web server (public subnet) and database server (private subnet) instances

    9. Create a new security group for the NAT instance
    10. Add HTTP and HTTPS inbound rules that allow traffic from the private subnets IP
    11. Create a NAT instance (public subnet)

    • Community AMIs
    • Search for amzn-ami-vpc-nat
    • Choose the first image
    • Diable Auto-assign Public IP
    • Add it to the NAT security group

    12. Create an Elastic IP
    12. Associate the Elastic IP to the NAT
    13. Disable Source/Destination Checks for the NAT
    14. Add the NAT instance as a route to the initial VPC RT

    Wednesday, 18 January 2017

    What are the AWS Services for DevOps?



    • AWS CodeCommit: AWS CodeCommit is a fully-managed source control service that makes it easy for companies to host secure and highly scalable private Git repositories. CodeCommit eliminates the need to operate your own source control system or worry about scaling its infrastructure. You can use CodeCommit to securely store anything from source code to binaries, and it works seamlessly with your existing Git tools.
    • AWS CodePipeline: AWS CodePipeline is a continuous integration and continuous delivery service for fast and reliable application and infrastructure updates. CodePipeline builds, tests, and deploys your code every time there is a code change, based on the release process models you define. This enables you to rapidly and reliably deliver features and updates. You can easily build out an end-to-end solution by using our pre-built plugins for popular third-party services like GitHub or integrating your own custom plugins into any stage of your release process.
    • AWS CodeBuild: AWS CodeBuild is a fully managed build service that compiles source code, runs tests, and produces software packages that are ready to deploy. With CodeBuild, you don’t need to provision, manage, and scale your own build servers. CodeBuild scales continuously and processes multiple builds concurrently, so your builds are not left waiting in a queue. You can get started quickly by using prepackaged build environments, or you can create custom build environments that use your own build tools. With CodeBuild, you are charged by the minute for the compute resources you use.
    • AWS CodeDeploy: AWS CodeDeploy is a service that automates code deployments to any instance, including Amazon EC2 instances and servers running on-premises. AWS CodeDeploy makes it easier for you to rapidly release new features, helps you avoid downtime during application deployment, and handles the complexity of updating your applications. You can use AWS CodeDeploy to automate software deployments, eliminating the need for error-prone manual operations, and the service scales with your infrastructure so you can easily deploy to one instance or thousands.


    What do you understand by this diagram?




    Ans: This diagram is showing DevOps as the intersection of development (software engineering), technology operations and quality assurance.

    What are the Advantage/Benefits of using AWS for DevOps? Why use AWS for DevOps?

    AWS DevOps Interview Question:
    What are the Advantage/Benefits of using AWS for DevOps? Why use AWS for DevOps?
    Ans:
    Below are the Benifits of using AWS for DevOps, Reasons for using AWS for DevOps




    Get Started Fast:
    Each AWS service is ready to use if you have an AWS account. There is no setup required or software to install.



    Fully Managed Services: 
    These services can help you take advantage of AWS resources quicker. You can worry less about setting up, installing, and operating infrastructure on your own. This lets you focus on your core product.


    Built for Scale: 
    You can manage a single instance or scale to thousands using AWS services. These services help you make the most of flexible compute resources by simplifying provisioning, configuration, and scaling.


    Programmable: 
    You have the option to use each service via the AWS Command Line Interface or through APIs and SDKs. You can also model and provision AWS resources and your entire AWS infrastructure using declarative AWS CloudFormation templates.


    Automation: 
    AWS helps you use automation so you can build faster and more efficiently. Using AWS services, you can automate manual tasks or processes such as deployments, development & test workflows, container management, and configuration management.

    Secure: 
    Use AWS Identity and Access Management (IAM) to set user permissions and policies. This gives you granular control over who can access your resources and how they access those resources.


    Large Partner Ecosystem: 
    AWS supports a large ecosystem of partners which integrate with and extend AWS services. Use your preferred third-party and open source tools with AWS to build an end-to-end solution. Visit here to learn more about our DevOps Partner Solutions.


    Pay-As-You-Go: 
    With AWS purchase services as you need them and only for the period when you plan to use them. AWS pricing has no upfront fees, termination penalties, or long term contracts. The AWS Free Tier helps you get started with AWS. Visit the pricing pages of each service to learn more.


    What are the Advantage/Benefits of DevOps? AWS DevOps Interview Questions


    • Speed: Move at high velocity so you can innovate for customers faster, adapt to changing markets better, and grow more efficient at driving business results. The DevOps model enables your developers and operations teams to achieve these results. For example, microservices and continuous delivery let teams take ownership of services and then release updates to them quicker.
    • Rapid Delivery: Increase the frequency and pace of releases so you can innovate and improve your product faster. The quicker you can release new features and fix bugs, the faster you can respond to your customers’ needs and build competitive advantage. Continuous integration and continuous delivery are practices that automate the software release process, from build to deploy.
    • Reliability:Ensure the quality of application updates and infrastructure changes so you can reliably deliver at a more rapid pace while maintaining a positive experience for end users. Use practices like continuous integration and continuous delivery to test that each change is functional and safe. Monitoring and logging practices help you stay informed of performance in real-time.
    • Scale: Operate and manage your infrastructure and development processes at scale. Automation and consistency help you manage complex or changing systems efficiently and with reduced risk. For example, infrastructure as code helps you manage your development, testing, and production environments in a repeatable and more efficient manner.

    • Improved Collaboration: Build more effective teams under a DevOps cultural model, which emphasizes values such as ownership and accountability. Developers and operations teams collaborate closely, share many responsibilities, and combine their workflows. This reduces inefficiencies and saves time (e.g. reduced handover periods between developers and operations, writing code that takes into account the environment in which it is run).
    • Security: Move quickly while retaining control and preserving compliance. You can adopt a DevOps model without sacrificing security by using automated compliance policies, fine-grained controls, and configuration management techniques. For example, using infrastructure as code and policy as code, you can define and then track compliance at scale.


    What is DevOps? AWS DevOps Interview Questions Answers

    DevOps is the combination of cultural philosophies, practices, and tools that increases an organization’s ability to deliver applications and services at high velocity: evolving and improving products at a faster pace than organizations using traditional software development and infrastructure management processes. This speed enables organizations to better serve their customers and compete more effectively in the market.



    Under a DevOps model, development and operations teams are no longer “siloed.” Sometimes, these two teams are merged into a single team where the engineers work across the entire application life-cycle, from development and test to deployment to operations, and develop a range of skills not limited to a single function. Quality assurance and security teams may also become more tightly integrated with development and operations and throughout the application life-cycle.
    These teams use practices to automate processes that historically have been manual and slow. They use a technology stack and tooling which help them operate and evolve applications quickly and reliably. These tools also help engineers independently accomplish tasks (for example, deploying code or provisioning infrastructure) that normally would have required help from other teams, and this further increases a team’s velocity.

    Ref: Amazon.com

    Tuesday, 17 January 2017

    Top 95 AWS VPC Interview Questions Answers PDF

    Here we come with most growing technology related interview questions, the technology is known as Amazon Virtual Private Cloud, Today is 18 Jan 2017 and we are posting this set after got lots of request from our previous article readers( 60 AWS Interview Questions) which become very famous and we got many comments and one guys send thanks email to us because he got selected and he respect our previous article with play big role in his selection.
    He has cracked "Adobe Systems" AWS interview and got jobs. We say thanks for such a kind email. :)
    And we want to get more such emails from you(readers) Best of luck...... pdf will be available soon

    TOP 95 AWS VPC INTERVIEW QUESTIONS ANSWERS

    1). What is Amazon Virtual Private Cloud (Amazon VPC)?

    2). What are the connectivity options for my VPC?

    3). How do you connect my VPC to the Internet?

    4). What are the components of Amazon VPC?

    4.1) What are the steps to build a custom VPC?

    5). Why should you use Amazon VPC, Advantage of using AWS VPC?

    6). What is the difference between stateful and stateless filtering?

    7). Within Amazon VPC, can you use SSH key pairs created for instances within Amazon EC2, and vice versa?

    8). Can Amazon EC2 instances within a VPC communicate with Amazon EC2 instances not within a VPC?

    9). Why can’t you ping the router, or my default gateway, that connects my subnets?

    10). Can you monitor the network traffic in your VPC?

    11). Within which Amazon EC2 region(s) is Amazon VPC available?

    12). Can a VPC span multiple Availability Zones?

    13). Can you use your existing AMIs in Amazon VPC?

    14). Can you employ Amazon CloudWatch within Amazon VPC?

    15). How do you specify which Availability Zone my Amazon EC2 instances are launched in?

    16). Are there any bandwidth limitations for Internet gateways? Do you need to be concerned about its availability? Can it be a single point of failure?

    17). How do you secure Amazon EC2 instances running within my VPC?

    18). What are the differences between security groups in a VPC and network ACLs in a VPC?

    19). How do you determine which Availability Zone my subnets are located in?

    20). When you call DescribeInstances(), do you see all of my Amazon EC2 instances, including those in EC2-Classic and EC2-VPC?

    21). When you call DescribeVolumes(), do you see all of my Amazon EBS volumes, including those in EC2-Classic and EC2-VPC?

    22). How many Amazon EC2 instances can you use within a VPC?

    23). Can you employ Auto Scaling within Amazon VPC?

    24). What is the IP range of a default VPC?

    25). How many default VPCs can you have?

    26). How many default subnets are in a default VPC?

    27). Can you launch Amazon EC2 Cluster Instances in a VPC?

    28). What is a default VPC?

    29). What are the advantage of a default VPC?

    30). What accounts are enabled for default VPC?

    31). How can you know if my account is configured to use a default VPC?

    32). Can you create other VPCs and use them in addition to my default VPC?

    33). Can you create additional subnets in my default VPC, such as private subnets?

    34). Will you need to know anything about Amazon VPC in order to use a default VPC?

    35). What are the differences between instances launched in EC2-Classic and EC2-VPC?

    36). Can you use my existing Amazon EBS snapshots?

    37). Can you boot an Amazon EC2 instance from an Amazon EBS volume within Amazon VPC?

    38). Can you use Amazon EC2 Reserved Instances with Amazon VPC?

    39). Do you need to have a VPN connection to use a default VPC?

    40). Can you delete a default VPC?

    41). Can you delete a default subnet?

    42). If you delete my side of a peering connection, will the other side still have access to my VPC?

    43). If you peer VPC A to VPC B and I peer VPC B to VPC C, does that mean VPCs A and C are peered?

    44). You have an existing EC2-Classic account. Can I get a default VPC?

    45). You really want a default VPC for my existing EC2 account. Is that possible?

    46). How are IAM accounts impacted by default VPC?

    47). Can you attach or detach one or more network interfaces to an EC2 instance while it’s running?

    48). What if your peering connection goes down?

    49). Can you create a peering connection to a VPC in a different region?

    50). Can you peer my VPC with a VPC belonging to another AWS account?

    51). Can you have more than two network interfaces attached to my EC2 instance?

    52). Can you attach a network interface in one Availability Zone to an instance in another Availability Zone?

    53). Can you attach a network interface in one VPC to an instance in another VPC?

    54). Can you use Elastic Network Interfaces as a way to host multiple websites requiring separate IP addresses on a single instance?

    55). Can you detach the primary interface (eth0) on my EC2 instance?

    56). Can you use AWS Direct Connect or hardware VPN connections to access VPCs I’m peered with?

    57). Can you peer two VPCs with matching IP address ranges?

    58). Do you need an Internet Gateway to use peering connections?

    59). Is VPC peering traffic within the region encrypted?

    60). Is there any bandwidth limitations for peering connections?

    61). What is ClassicLink?

    62). How do you use ClassicLink?

    63). Does the EC2-Classic instance become a member of the VPC?

    64). Will ClassicLink settings on my EC2-Classic instance persist through stop/start cycles?

    65). Can you modify the VPC route tables? How?

    66). Can you specify which subnet will use which gateway as its default?

    67). Can you use the AWS Management Console to control and manage Amazon VPC?

    68). How many VPCs, subnets, Elastic IP addresses, Internet gateways, customer gateways, virtual private gateways, and VPN connections can you create?

    69). Does the Amazon VPC VPN Connection have a Service Level Agreement (SLA)?

    70). What does an Amazon VPC router do?

    71). Does Amazon VPC support multicast or broadcast?

    72). How do instances in a VPC access the Internet?

    73). How do instances without public IP addresses access the Internet?

    74). How does a hardware VPN connection work with Amazon VPC?

    75). What is IPsec?

    76). Which customer gateway devices can I use to connect to Amazon VPC?

    77). Name any VPCs for which you cannot enable ClassicLink?

    78). Can traffic from an EC2-Classic instance travel through the Amazon VPC and egress through the Internet gateway, virtual private gateway, or to peered VPCs?

    79). Does ClassicLink affect the access control between the EC2-Classic instance, and other instances that are in the EC2-Classic platform?

    80). What tools are available to me to help troubleshoot my Hardware VPN configuration?

    81). How do I connect a VPC to my corporate datacenter?

    82). Are there any VPN connection throughput limitations?

    83). Can you NAT your CGW behind a router or firewall?

    84). What IP address do you use for your CGW address?

    85). How do you assign IP address ranges to VPCs?

    86). What IP address ranges are assigned to a default VPC?

    87). Can you assign any IP address to an instance?

    88). Can you assign multiple IP addresses to an instance?

    89). What defines billable VPN connection-hours?

    90). Can you change a VPC's size?

    91). How many subnets can I create per VPC?

    92). Is there a limit on how large or small a subnet can be?

    93). How do you assign private IP addresses to Amazon EC2 instances within a VPC?

    94). How do you disable NAT-T on my connection?

    95). Can Amazon EC2 instances within a VPC communicate with Amazon S3?

    Must read our previous article..... Click here 

    Can Amazon EC2 instances within a VPC communicate with Amazon S3?

    Yes. There are multiple options for your resources within a VPC to communicate with Amazon S3. You can use VPC Endpoint for S3, which makes sure all traffic remains within Amazon's network and enables you to apply additional access policies to your Amazon S3 traffic. You can use an Internet gateway to enable Internet access from your VPC and instances in the VPC can communicate with Amazon S3. You can also make all traffic to Amazon S3 traverse the Direct Connect or VPN connection, egress from your datacenter, and then re-enter the public AWS network.

    How do you disable NAT-T on my connection?

    You will need to disable NAT-T on your device. If you don’t plan on using NAT-T and it is not disabled on your device, we will attempt to establish a tunnel over UDP port 4500. If that port is not open the tunnel will not establish.

    How do you assign private IP addresses to Amazon EC2 instances within a VPC?

    When you launch an Amazon EC2 instance within a VPC, you may optionally specify the primary private IP address for the instance. If you do not specify the primary private IP address, AWS automatically addresses it from the IP address range you assign to that subnet. You can assign secondary private IP addresses when you launch an instance, when you create an Elastic Network Interface, or any time after the instance has been launched or the interface has been created.

    What defines billable VPN connection-hours?

    VPN connection-hours are billed for any time your VPN connections are in the "available" state. You can determine the state of a VPN connection via the AWS Management Console, CLI, or API. If you no longer wish to use your VPN connection, you simply terminate the VPN connection to avoid being billed for additional VPN connection-hours.

    Can you assign multiple IP addresses to an instance?

    Yes. You can assign one or more secondary private IP addresses to an Elastic Network Interface or an EC2 instance in Amazon VPC. The number of secondary private IP addresses you can assign depends on the instance type. See the EC2 User Guide for more information on the number of secondary private IP addresses that can be assigned per instance type.

    Can you assign any IP address to an instance?

    You can assign any IP address to your instance as long as it is:

    • Part of the associated subnet's IP address range
    • Not reserved by Amazon for IP networking purposes
    • Not currently assigned to another interface

    How do you assign IP address ranges to VPCs?

    You assign a single Classless Internet Domain Routing (CIDR) IP address block when you create a VPC. Subnets within a VPC are addressed from this range by you. A VPC can be assigned at most one (1) IP address range at any given time; addressing a VPC from multiple IP address ranges is currently not supported. Please note that while you can create multiple VPCs with overlapping IP address ranges, doing so will prohibit you from connecting these VPCs to a common home network via the hardware VPN connection. For this reason we recommend using non-overlapping IP address ranges.  You can allocate an Amazon-provided IPv6 CIDR block to your VPC.

    Are there any VPN connection throughput limitations?

    Amazon does not enforce any restrictions on VPN throughput. However, other factors, such as the cryptographic capability of your customer gateway, the capacity of your Internet connection, average packet size, the protocol being used (TCP vs. UDP), and the network latency between your customer gateway and the virtual private gateway can affect throughput. 

    How do I connect a VPC to my corporate datacenter?

    Establishing a hardware VPN connection between your existing network and Amazon VPC allows you to interact with Amazon EC2 instances within a VPC as if they were within your existing network. AWS does not perform network address translation (NAT) on Amazon EC2 instances within a VPC accessed via a hardware VPN connection.

    Name any VPCs for which you cannot enable ClassicLink?

    ClassicLink cannot be enabled for a VPC that has a Classless Inter-Domain Routing (CIDR) that is within the 10.0.0.0/8 range, with the exception of 10.0.0.0/16 and 10.1.0.0/16.  In addition, ClassicLink cannot be enabled for any VPC that has a route table entry pointing to the 10.0.0.0/8 CIDR space to a target other than "local".

    Which customer gateway devices can I use to connect to Amazon VPC?

    There are two types of VPN connections that you can create: statically-routed VPN connections and dynamically-routed VPN connections. Customer gateway devices supporting statically-routed VPN connections must be able to:

    • Establish IKE Security Association using Pre-Shared Keys
    • Establish IPsec Security Associations in Tunnel mode
    • Utilize the AES 128-bit or 256-bit encryption function
    • Utilize the SHA-1 or SHA-2 (256) hashing function
    • Utilize Diffie-Hellman (DH) Perfect Forward Secrecy in "Group 2" mode, or one of the additional DH groups we support
    • Perform packet fragmentation prior to encryption

    In addition to the above capabilities, devices supporting dynamically-routed VPN connections must be able to:

    • Establish Border Gateway Protocol (BGP) peerings
    • Bind tunnels to logical interfaces (route-based VPN)
    • Utilize IPsec Dead Peer Detection

    What is IPsec?

    IPsec is a protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a data stream. 

    How does a hardware VPN connection work with Amazon VPC?

    A hardware VPN connection connects your VPC to your datacenter. Amazon supports Internet Protocol security (IPsec) VPN connections. Data transferred between your VPC and datacenter routes over an encrypted VPN connection to help maintain the confidentiality and integrity of data in transit. An Internet gateway is not required to establish a hardware VPN connection.

    How do instances without public IP addresses access the Internet?

    Instances without public IP addresses can access the Internet in one of two ways:
    Instances without public IP addresses can route their traffic through a NAT gateway or a NAT instance to access the Internet. These instances use the public IP address of the NAT gateway or NAT instance to traverse the Internet. The NAT gateway or NAT instance allows outbound communication but doesn’t allow machines on the Internet to initiate a connection to the privately addressed instances.
    For VPCs with a hardware VPN connection or Direct Connect connection, instances can route their Internet traffic down the virtual private gateway to your existing datacenter. From there, it can access the Internet via your existing egress points and network security/monitoring devices.

    How do instances in a VPC access the Internet?

    You can use public IP addresses, including Elastic IP addresses (EIPs), to give instances in the VPC the ability to both directly communicate outbound to the Internet and to receive unsolicited inbound traffic from the Internet (e.g., web servers).  You can also use the solutions in the next question.

    What does an Amazon VPC router do?

    An Amazon VPC router enables Amazon EC2 instances within subnets to communicate with Amazon EC2 instances in other subnets within the same VPC. The VPC router also enables subnets, Internet gateways, and virtual private gateways to communicate with each other. Network usage data is not available from the router; however, you can obtain network usage statistics from your instances using Amazon CloudWatch.

    How many VPCs, subnets, Elastic IP addresses, Internet gateways, customer gateways, virtual private gateways, and VPN connections can you create?

    You can have:

    • Five Amazon VPCs per AWS account per region
    • Two hundred subnets per Amazon VPC
    • Five Amazon VPC Elastic IP addresses per AWS account per region
    • One Internet gateway per VPC
    • Five virtual private gateways per AWS account per region
    • Fifty customer gateways per AWS account per region
    • Ten IPsec VPN Connections per virtual private gateway
    • See the VPC User Guide for more information on VPC limits.

    Does the EC2-Classic instance become a member of the VPC?

    The EC2-Classic instance does not become a member of the VPC. It becomes a member of the VPC Security Group that was associated with the instance. All the rules and references to the VPC Security Group apply to communication between instances in EC2-Classic instance and resources within the VPC.

    How do you use ClassicLink?

    In order to use ClassicLink, you first need to enable at least one VPC in your account for ClassicLink. Then you associate a Security Group from the VPC with the desired EC2-Classic instance. The EC2-Classic instance is now linked to the VPC and is a member of the selected Security Group in the VPC. Your EC2-Classic instance cannot be linked to more than one VPC at the same time.

    What is ClassicLink?

    Amazon Virtual Private Cloud (VPC) ClassicLink allows EC2 instances in the EC2-Classic platform to communicate with instances in a VPC using private IP addresses. To use ClassicLink, enable it for a VPC in your account, and associate a Security Group from that VPC with an instance in EC2-Classic. All the rules of your VPC Security Group will apply to communications between instances in EC2-Classic and instances in the VPC.

    Is there any bandwidth limitations for peering connections?

    Bandwidth between instances in peered VPCs is no different than bandwidth between instances in the same VPC. Note: A placement group can span peered VPCs; however, you will not get full-bisection bandwidth between instances in peered VPCs. Read more about Placement Groups.

    What if your peering connection goes down?

    AWS uses the existing infrastructure of a VPC to create a VPC peering connection; it is neither a gateway nor a VPN connection, and does not rely on a separate piece of physical hardware. There is no single point of failure for communication or a bandwidth bottleneck.

    You really want a default VPC for my existing EC2 account. Is that possible?

    Yes, however, we can only enable an existing account for a default VPC if you have no EC2-Classic resources for that account in that region. Additionally, you must terminate all non-VPC provisioned Elastic Load Balancers, Amazon RDS, Amazon ElastiCache, and Amazon Redshift resources in that region. After your account has been configured for a default VPC, all future resource launches, including instances launched via Auto Scaling, will be placed in your default VPC. To request your existing account be setup with a default VPC, contact AWS Support. We will review your request and your existing AWS services and EC2-Classic presence to determine if you are eligible for a default VPC.

    You have an existing EC2-Classic account. Can I get a default VPC?

    The simplest way to get a default VPC is to create a new account in a region that is enabled for default VPCs, or use an existing account in a region you've never been to before, as long as the Supported Platforms attribute for that account in that region is set to "EC2-VPC".

    Can you delete a default subnet?

    Yes, but once deleted, it’s gone. Your future instance launches will be placed in your remaining default subnet(s).

    Do you need to have a VPN connection to use a default VPC?

    No. Default VPCs are attached to the Internet and all instances launched in default subnets in the default VPC automatically receive public IP addresses. You can add a VPN connection to your default VPC if you choose.

    Can you use Amazon EC2 Reserved Instances with Amazon VPC?

    Yes. You can reserve an instance in Amazon VPC when you purchase Reserved Instances. When computing your bill, AWS does not distinguish whether your instance runs in Amazon VPC or standard Amazon EC2. AWS automatically optimizes which instances are charged at the lower Reserved Instance rate to ensure you always pay the lowest amount. However, your instance reservation will be specific to Amazon VPC. Please see the Reserved Instances page for further details.

    Can you boot an Amazon EC2 instance from an Amazon EBS volume within Amazon VPC?

    Yes, however, an instance launched in a VPC using an Amazon EBS-backed AMI maintains the same IP address when stopped and restarted. This is in contrast to similar instances launched outside a VPC, which get a new IP address. The IP addresses for any stopped instances in a subnet are considered unavailable.

    Can you use my existing Amazon EBS snapshots?

    Yes, you may use Amazon EBS snapshots if they are located in the same region as your VPC. More details are available in the Amazon EC2 Region and Availability Zone FAQ.

    Will you need to know anything about Amazon VPC in order to use a default VPC?

    No. You can use the AWS Management Console, AWS EC2 CLI, or the Amazon EC2 API to launch and manage EC2 instances and other AWS resources in a default VPC. AWS will automatically create a default VPC for you and will create a default subnet in each Availability Zone in the AWS region. Your default VPC will be connected to an Internet gateway and your instances will automatically receive public IP addresses, just like EC2-Classic.

    How can you know if my account is configured to use a default VPC?

    The Amazon EC2 console indicates which platforms you can launch instances in for the selected region, and whether you have a default VPC in that region. Verify that the region you'll use is selected in the navigation bar. On the Amazon EC2 console dashboard, look for "Supported Platforms" under "Account Attributes". If there are two values, EC2-Classic and EC2-VPC, you can launch instances into either platform. If there is one value, EC2-VPC, you can launch instances only into EC2-VPC. Your default VPC ID will be listed under "Account Attributes" if your account is configured to use a default VPC. You can also use the EC2 DescribeAccountAttributes API or CLI to describe your supported platforms.

    What accounts are enabled for default VPC?

    If your AWS account was created after March 18, 2013 your account may be able to launch resources in a default VPC. See this Forum Announcement to determine which regions have been enabled for the default VPC feature set. Also, accounts created prior to the listed dates may utilize default VPCs in any default VPC enabled region in which you’ve not previously launched EC2 instances or provisioned Amazon Elastic Load Balancing, Amazon RDS, Amazon ElastiCache, or Amazon Redshift resources.

    What are the advantage of a default VPC?

    When you launch resources in a default VPC, you can benefit from the advanced networking functionalities of Amazon VPC (EC2-VPC) with the ease of use of Amazon EC2 (EC2-Classic). You can enjoy features such as changing security group membership on the fly, security group egress filtering, multiple IP addresses, and multiple network interfaces without having to explicitly create a VPC and launch instances in the VPC.

    What is a default VPC?

    A default VPC is a logically isolated virtual network in the AWS cloud that is automatically created for your AWS account the first time you provision Amazon EC2 resources. When you launch an instance without specifying a subnet-ID, your instance will be launched in your default VPC.

    How many Amazon EC2 instances can you use within a VPC?

    You can run any number of Amazon EC2 instances within a VPC, so long as your VPC is appropriately sized to have an IP address assigned to each instance. You are initially limited to launching 20 Amazon EC2 instances at any one time and a maximum VPC size of /16 (65,536 IPs). If you would like to increase these limits, please complete the following form.

    How do you determine which Availability Zone my subnets are located in?

    When you create a subnet you must specify the Availability Zone in which to place the subnet. When using the VPC Wizard, you can select the subnet's Availability Zone in the wizard confirmation screen. When using the API or the CLI you can specify the Availability Zone for the subnet as you create the subnet. If you don’t specify an Availability Zone, the default "No Preference" option will be selected and the subnet will be created in an available Availability Zone in the region.

    What are the differences between security groups in a VPC and network ACLs in a VPC?

    Security groups in a VPC specify which traffic is allowed to or from an Amazon EC2 instance. Network ACLs operate at the subnet level and evaluate traffic entering and exiting a subnet. Network ACLs can be used to set both Allow and Deny rules. Network ACLs do not filter traffic between instances in the same subnet. In addition, network ACLs perform stateless filtering while security groups perform stateful filtering.

    How do you secure Amazon EC2 instances running within my VPC?

    Amazon EC2 security groups can be used to help secure instances within an Amazon VPC. Security groups in a VPC enable you to specify both inbound and outbound network traffic that is allowed to or from each Amazon EC2 instance. Traffic which is not explicitly allowed to or from an instance is automatically denied.

    In addition to security groups, network traffic entering and exiting each subnet can be allowed or denied via network Access Control Lists (ACLs).

    Can you use your existing AMIs in Amazon VPC?

    You can use AMIs in Amazon VPC that are registered within the same region as your VPC. For example, you can use AMIs registered in us-east-1 with a VPC in us-east-1. More information is available in the Amazon EC2 Region and Availability Zone FAQ.

    Can Amazon EC2 instances within a VPC communicate with Amazon EC2 instances not within a VPC?

    Yes. If an Internet gateway has been configured, Amazon VPC traffic bound for Amazon EC2 instances not within a VPC traverses the Internet gateway and then enters the public AWS network to reach the EC2 instance. If an Internet gateway has not been configured, or if the instance is in a subnet configured to route through the virtual private gateway, the traffic traverses the VPN connection, egresses from your datacenter, and then re-enters the public AWS network.

    What is the difference between stateful and stateless filtering?

    Stateful filtering tracks the origin of a request and can automatically allow the reply to the request to be returned to the originating computer. For example, a stateful filter that allows inbound traffic to TCP port 80 on a webserver will allow the return traffic, usually on a high numbered port (e.g., destination TCP port 63, 912) to pass through the stateful filter between the client and the webserver. The filtering device maintains a state table that tracks the origin and destination port numbers and IP addresses. Only one rule is required on the filtering device: Allow traffic inbound to the web server on TCP port 80.

    Stateless filtering, on the other hand, only examines the source or destination IP address and the destination port, ignoring whether the traffic is a new request or a reply to a request. In the above example, two rules would need to be implemented on the filtering device: one rule to allow traffic inbound to the web server on TCP port 80, and another rule to allow outbound traffic from the webserver (TCP port range 49, 152 through 65, 535).

    Why should you use Amazon VPC, Advantage of using AWS VPC?

    Amazon VPC enables you to build a virtual network in the AWS cloud - no VPNs, hardware, or physical datacenters required. You can define your own network space and control how your network, and the Amazon EC2 resources inside your network, is exposed to the Internet. You can also leverage the greatly enhanced security options in Amazon VPC to provide more granular access both to and from the Amazon EC2 instances in your virtual network.

    What are the components of Amazon VPC?

    Amazon VPC comprises a variety of objects that will be familiar to customers with existing networks:

    • A Virtual Private Cloud (VPC): A logically isolated virtual network in the AWS cloud. You define a VPC’s IP address space from a range you select.
    • Subnet: A segment of a VPC’s IP address range where you can place groups of isolated resources.
    • Internet Gateway: The Amazon VPC side of a connection to the public Internet.
    • NAT Gateway: A highly available, managed Network Address Translation (NAT) service for your resources in a private subnet to access the Internet.
    • Hardware VPN Connection: A hardware-based VPN connection between your Amazon VPC and your datacenter, home network, or co-location facility.
    • Virtual Private Gateway: The Amazon VPC side of a VPN connection.
    • Customer Gateway: Your side of a VPN connection.
    • Router: Routers interconnect subnets and direct traffic between Internet gateways, virtual private gateways, NAT gateways, and subnets.
    • Peering Connection: A peering connection enables you to route traffic via private IP addresses between two peered VPCs.
    • VPC Endpoint for S3: Enables Amazon S3 access from within your VPC without using an Internet gateway or NAT, and allows you to control the access using VPC endpoint policies.
    • Egress-only Internet Gateway: A stateful gateway to provide egress only access for IPv6 traffic from the VPC to the Internet


    Find job here...