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 is 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?

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 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.

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.

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?

Traffic from an EC2-Classic instance can only be routed to private IP addresses within the VPC. They will not be routed to any destinations outside the VPC, including Internet gateway, virtual private gateway, or peered VPC destinations.

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

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.

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.

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

The ClassicLink connection will not persist through stop/start cycles of the EC2-Classic instance. The EC2-Classic instance will need to be linked back to a VPC after it is stopped and started. However, the ClassicLink connection will persist through instance reboot cycles.

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.

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.

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.

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.

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 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


What are the connectivity options for my VPC?

You may connect your VPC to:

  • The Internet (via an Internet gateway)
  • Your corporate data center using a Hardware VPN connection (via the virtual private gateway)
  • Both the Internet and your corporate data center (utilizing both an Internet gateway and a virtual private gateway)
  • Other AWS services (via Internet gateway, NAT, virtual private gateway, or VPC endpoints)
  • Other VPCs (via VPC peering connections)

What is Amazon Virtual Private Cloud (Amazon VPC)?

Amazon VPC lets you provision a logically isolated section of the Amazon Web Services (AWS) cloud where you can launch AWS resources in a virtual network that you define. You have complete control over your virtual networking environment, including selection of your own IP address range, creation of subnets, and configuration of route tables and network gateways. You can also create a hardware Virtual Private Network (VPN) connection between your corporate datacenter and your VPC and leverage the AWS cloud as an extension of your corporate datacenter.

You can easily customize the network configuration for your Amazon VPC. For example, you can create a public-facing subnet for your web servers that have access to the Internet, and place your backend systems such as databases or application servers in a private-facing subnet with no Internet access. You can leverage multiple layers of security, including security groups and network access control lists, to help control access to Amazon EC2 instances in each subnet.
Get Started with AWS for Free

The following diagram shows the architecture that you'll create as you complete the exercise in this guide. The security group that you set up and associate with the instance allows traffic only through specific ports, locking down communication with the instance according to the rules that you specify. Using an Elastic IP address (EIP) enables an instance in a VPC, which is otherwise private, to be reached from the Internet through an Internet gateway (for example, it could act as a web server).

Differences between EC2-Classic and EC2-VPC / EC2-Classic vs EC2-VPC

The following table summarizes the differences between EC2-Classic and EC2-VPC.
EC2-ClassicEC2-VPC
You can create up to 500 security groups per region.
You can create up to 500 security groups per VPC.
You can add up to 100 rules to a security group.
You can add up to 50 rules to a security group.
You can add rules for inbound traffic only.
You can add rules for inbound and outbound traffic.
You can assign up to 500 security groups to an instance.
You can assign up to 5 security groups to a network interface.
You can reference security groups from other AWS accounts.
You can reference security groups from your VPC or from a peer VPC in a VPC peering connection only. The peer VPC can be in a different account.
After you launch an instance, you can't change the security groups assigned to it.
You can change the security groups assigned to an instance after it's launched.
When you add a rule to a security group, you don't have to specify a protocol, and only TCP, UDP, or ICMP are available.
When you add a rule to a security group, you must specify a protocol, and it can be any protocol with a standard protocol number, or all protocols (see Protocol Numbers).
When you add a rule to a security group, you must specify port numbers (for TCP or UDP).
When you add a rule to a security group, you can specify port numbers only if the rule is for TCP or UDP, and you can specify all port numbers.
Security groups that are referenced in another security group's rules cannot be deleted.Security groups that are referenced in another security group's rules can be deleted if the security groups are in different VPCs. If the referenced security group is deleted, the rule is marked as stale. You can use the describe-stale-security-groups AWS CLI command to identify stale rules.
You cannot specify an IPv6 CIDR block or an IPv6 address as the source or destination in a security group rule.You can specify an IPv6 CIDR block or an IPv6 address as the source or destination in a security group rule.

Can you use threads and processes in my AWS Lambda function code?

Yes. AWS Lambda allows you to use normal language and operating system features, such as creating additional threads and processes. Resources allocated to the Lambda function, including memory, execution time, disk, and network use, must be shared among all the threads/processes it uses. You can launch processes using any language supported by Amazon Linux.

What is an event source?

An event source is an AWS service or developer-created application that produces events that trigger an AWS Lambda function to run. Some services publish these events to Lambda by invoking the cloud function directly (for example, Amazon S3). Lambda can also poll resources in other services that do not publish events to Lambda. For example, Lambda can pull records from a Kinesis stream and execute a Lambda function for each message in the stream.
Many other services, such as AWS CloudTrail, can act as event sources simply by logging to Amazon S3 and using S3 bucket notifications to trigger AWS Lambda functions.

How do you make an AWS Lambda function respond to changes in an Amazon S3 bucket?

From the AWS Lambda console, you can select a function and associate it with notifications from an Amazon S3 bucket. Alternatively, you can use the Amazon S3 console and configure the bucket’s notifications to send to your AWS Lambda function. This same functionality is also available through the AWS SDK and CLI.

When should you use Lambda@Edge?

Lambda@Edge is optimized for use cases where all the information you need to make a decision is available at the CloudFront edge, within the function and the request. This means that use cases where you are looking to make decisions on how to serve content based on user characteristics (e.g., location, client device, etc) can now be executed and served right from the edge without having to be routed back to a centralized server.

How do you use Lambda@Edge?

To use Lambda@Edge, you just upload your code to AWS Lambda and configure your function to be triggered in response to Amazon CloudFront requests. Your code must satisfy the Lambda@Edge service limits. Lambda@Edge only supports Node.js at this time.

What is Lambda@Edge?

Lambda@Edge allows you to run code at global AWS edge locations without provisioning or managing servers, responding to end users at the lowest network latency. You just upload your Node.js code to AWS Lambda and configure your function to be triggered in response to Amazon CloudFront requests (i.e., when a viewer request lands, when a request is forwarded to or received back from the origin, and right before responding back to the end user). The code is then ready to execute at every AWS edge location when a request for content is received, and scales with the volume of requests across CloudFront edge locations.

How do you troubleshoot failures in an AWS Lambda function?

AWS Lambda automatically integrates with Amazon CloudWatch logs, creating a log group for each Lambda function and providing basic application lifecycle event log entries, including logging the resources consumed for each use of that function. You can easily insert additional logging statements into your code. You can also call third-party logging APIs in your Lambda function. Visit Troubleshooting Lambda functions to learn more. Amazon CloudWatch Logs rates will apply.

Is there a limit to the number of AWS Lambda functions you can execute at once?

No. AWS Lambda is designed to run many instances of your functions in parallel. However, AWS Lambda has a default safety throttle of 100 concurrent executions per account per region. If you wish to submit a request to increase the throttle of 100 concurrent executions you can visit our Support Center, click “Open a new case”, and file a service limit increase request.

What is an AWS Lambda function?

The code you run on AWS Lambda is uploaded as a “Lambda function”. Each function has associated configuration information, such as its name, description, entry point, and resource requirements. The code must be written in a “stateless” style i.e. it should assume there is no affinity to the underlying compute infrastructure. Local file system access, child processes, and similar artifacts may not extend beyond the lifetime of the request, and any persistent state should be stored in Amazon S3, Amazon DynamoDB, or another Internet-available storage service. Lambda functions can include libraries, even native ones.

When should you use AWS Lambda versus Amazon EC2?

Amazon Web Services offers a set of compute services to meet a range of needs.
Amazon EC2 offers flexibility, with a wide range of instance types and the option to customize the operating system, network and security settings, and the entire software stack, allowing you to easily move existing applications to the cloud. With Amazon EC2 you are responsible for provisioning capacity, monitoring fleet health and performance, and designing for fault tolerance and scalability. AWS Elastic Beanstalk offers an easy-to-use service for deploying and scaling web applications in which you retain ownership and full control over the underlying EC2 instances. Amazon EC2 Container Service is a scalable management service that supports Docker containers and allows you to easily run distributed applications on a managed cluster of Amazon EC2 instances.

AWS Lambda makes it easy to execute code in response to events, such as changes to Amazon S3 buckets, updates to an Amazon DynamoDB table, or custom events generated by your applications or devices. With Lambda you do not have to provision your own instances; Lambda performs all the operational and administrative activities on your behalf, including capacity provisioning, monitoring fleet health, applying security patches to the underlying compute resources, deploying your code, running a web service front end, and monitoring and logging your code. AWS Lambda provides easy scaling and high availability to your code without additional effort on your part.

How do you enable and disable the VPC support for my Lambda function?

To enable VPC support, you need to specify one or more subnets in a single VPC and a security group as part of your function configuration. To disable VPC support, you need to update the function configuration and specify an empty list for the subnet and security group. You can change these settings using the AWS APIs, CLI, or AWS Lambda Management Console. 

What are the best Practices for Working with AWS Lambda Functions?

The following are recommended best practices for using AWS Lambda:

  • Write your Lambda function code in a stateless style, and ensure there is no affinity between your code and the underlying compute infrastructure.
  • Instantiate AWS clients outside the scope of the handler to take advantage of connection re-use.
  • Make sure you have set +rx permissions on your files in the uploaded ZIP to ensure Lambda can execute code on your behalf.
  • Lower costs and improve performance by minimizing the use of startup code not directly related to processing the current event.
  • Use the built-in CloudWatch monitoring of your Lambda functions to view and optimize request latencies.
  • Delete old Lambda functions that you are no longer using.


What are the limitations of AWS Lambda?

AWS Lambda Limits
Every Lambda function is allocated with a fixed amount of specific resources regardless of the memory allocation, and each function is allocated with a fixed amount of code storage per function and per account.
The following table lists the run-time resource limits for a Lambda function per invocation.

AWS Lambda Resource Limits
ResourceDefault Limit
Ephemeral disk capacity ("/tmp" space)512 MB
Number of file descriptors1,024
Number of processes and threads (combined total)1,024
Maximum execution duration per request300 seconds
Invoke request body payload size (RequestResponse)6 MB
Invoke request body payload size (Event)128 K
Invoke response body payload size (RequestResponse)6 MB
AWS Lambda Deployment Limits
ItemDefault Limit
Lambda function deployment package size (.zip/.jar file)50 MB
Total size of all the deployment packages that can be uploaded per region75 GB
Size of code/dependencies that you can zip into a deployment package (uncompressed zip/jar size)250 MB
Total size of environment variables set4 KB

What Is AWS Lambda? AWS Interview Questions 2017

AWS Lambda is a compute service that lets you run code without provisioning or managing servers. AWS Lambda executes your code only when needed and scales automatically, from a few requests per day to thousands per second. You pay only for the compute time you consume - there is no charge when your code is not running. With AWS Lambda, you can run code for virtually any type of application or backend service - all with zero administration. AWS Lambda runs your code on a high-availability compute infrastructure and performs all of the administration of the compute resources, including server and operating system maintenance, capacity provisioning and automatic scaling, code monitoring and logging.

Monday, 16 January 2017

Top 20 Instagram.com Interview Questions with Sample Answers

Below you will find social networking site Instagram.com interview questions and sample answers in order to help you handle the question quickly and effectively to secure you the role you desire.


TOP 20 INSTAGRAM INTERVIEW QUESTIONS
1. Has anything happened to you like you has made some poor decisions or has done something that just did not turn out right?
Answer: Always try to avoid question like this which will show your inefficiency if answered so you can say no that there is nothing happened in your like this. But keep your answer positive and don't give them any doubt that you are hiding anything.

2. What do you believe in hard work or smart work?
Answer: Same as the last question you need to tell your interviewer that what you actually prefer while working, hard work or smart work. What is best for you, hard work or smart work? As you know in today's world person achieving success soon is only possible by doing smart work while on the other side hard work make it a long process. According to me everyone must work smartly than hardly working which would pay you on along run. So what do you think which one do you prefer working smartly or working hard and same you need to discuss with your interviewer with reasons that why.

3. Tell me about the time when you had difficulties in the past with your supervisor.
Answer: This question is to determine your future actions by knowing your past actions so be careful while answering this question. First you need to take time to think about career and the times you have had problem with your supervisor and how you happily you dealt with it. You don't need to be too honest here because your negative answer can affect your interview. So answer in a positive way only and avoid this situation by saying no that you have never faced difficulty with your supervisors.
Example Answer: Never, I have my opinions about how much supervision, guidance and feedback i need, but never a difficulty. My supervisors have generally been my favorite co-workers. I don't like to engage in bickering and complaining that often occurs amongst unaligned team members.


4. Tell me about your specific performance at you last company as a reason to hire you.
Answer: Same you need to praise your skills here to your interviewer to make them believe that you will be an asset for the company not liability. Interviewer just want strong proof for your effectiveness and effective skills that you are having which will lead to contribute in organizational goals if hired. So he/ she just want to make them sure for hiring you, they want strong reasons to hire you. So simple sell yourself that how effectively you can as same I said in another question like this which which questions your abilities and skills.

5. Tell me about the work which you did not want to do but still motivated yourself to complete it?
Answer: Here you need to describe the situation when you motivated yourself to work when you did not want to do that. Share the example of that situation and in what ways you motivated yourself. I n order to motivate yourself, you have to have some kind of reward at the end and by this also you can motivate yourself to work more. Example Answer: When I had a heavy workload which I had to complete in the same day and I did not want to complete the task but I was confident that I could get the job done the result was very effective and I was satisfied with my work.

6. What keeps you always motivated you to work hard in difficult times?
Answer: Keeping motivated yourself in difficult time is very important and the same thing your interviewer trying to see how you kept yourself motivated. There are many ways to keep yourself motivated in difficult times like:
*Take control over what you can, and stop worrying about what you can’t *Read and listen to positive information *Be with positive people as often as possible *Learn from your mistakes, instead of repeating them *Build a support team

7. Discuss about the situation when you had to address an angry client, How you handled the situation?
Answer: Here interviewer is trying to find out that do you ability to handle there angry client or not, it is same as handling an difficult customers. So as always you need explain by giving of particular situation with the methids you use to deal with angry customers. Here are the method to deal with angry customers: *Remain calm and adjust your mindset *Listen actively to what the customer is saying *Separate your feelings from the situation *Repeat the customer's concerns *Actively sympathize *Apologize *Call your manager over if the customer asks to do.

8. Did you made any unpopular decision recently?
Answer: Here interviewer is just trying to find out that are you able to make unpopular decision or not. Here you need to show that yes you can make unpopular decision and also tell them how. You just need to give some examples of your recent unpopular decisions to your interviewer with the outcomes. Show them that you have the ability like popular manager to make unpopular decisions. Keep notice that your unpopular decision should focus on process satisfaction, personal satisfaction and product satisfaction.

9. What stresses you out on the job?
Answer: Here interviewer is trying to see that how you cope up with stress at work or do you have skill of effective stress management. You should know that effective stress management starts with identifying your sources of stress and you should be aware about to easily cope up with stress.
Here are the steps:
*Track your stressors
*Develop healthy responses
*Establish boundaries
*Take time to recharge
*Learn how to relax
*Talk to your supervisor
*Get some support

10. If you got a chance, what would you change from your past?
Answer: Nothing. You don't need to show your interviewer that you have guilt or regret for the things you have done in your life. Everything happens for a reason so you should believe in experience everything for bad as well good times and learn lessons from the past and should focus on the future and don't need to repeat the past mistakes. Example
Answer: I would not change anything from past because it’s made me who I am today. You have to remember: you need to crack some eggs to make omelets. And I crack some eggs.

11. How you respond to problems with coworkers?
Answer: Here interviewer wants to know that how you will respond to problems with coworkers. You need to answer in positive tone only. And share the steps am mentioning here to how to respond to problems with coworkers:
*Giving in
*Avoiding the conflict
*Fighting it out
*Compromising
*Working together

12. Have you ever undertook a project that demanded a lot of initiative?
Answer: Here interviewer is trying to check that how good you are in taking challenges like this and how you take no. of initiative to complete a particular project successfully. Explain the situation of this challenge by giving one example to make your answer relevant. Discuss what was so challenging for that project, what steps you took to face that challenge, how you completed that project and what the actual outcome was.
Example Answer: There was a Horsham project for them museum where you had to take images of the artifacts there. I used my own initiative and came up with ideas that no one else would think of which then helped me win the competition. 0   0

13. How you complete a written assignment?
Answer: Here interviewer wants to know that how you go about completing a written assignment and how much you are good in this. Discuss your own ways of completing an assignments.
Here are some steps like:
*Brainstorm a flood of ideas on the subject you are working
*Do not embroil your mind too much with grammatical correction
*Fashioned all selected ideas into workable whole
*Choose the possible storage where your ideas can be placed
*Make sure that all the possible sources of disturbance have already been mitigated
*Drive on with your work
*Get all the possible sources of help on the table and go on to finish your assignment off.

14. Which was your favorite class at college? Why?
Answer: It’s totally up to you to how to answer this question. Interviewer want to see your college part that how you were in your college time, in what things you were interested. So answer this question in your only but avoid saying any stupid things. Explain your answer with reason.
Example Answer: My favorite class at college was the business policy. I found this a really fantastic subject because it is a something which is interesting and comes daily in use. Every day in newspaper you can see examples of making new policies put into action. The other reason why I enjoyed the class because it was a class of growing up students and that time is special in every one's life.

15. If hired, what would you do on your first day of the job?
Answer: Here interviewer is trying to find out your planning that what are your plans to do after getting hired and how much you are confident that you will get hired. You answer to this question will show your thoughts and consideration for how you will spend this time constructively.
Things to do on your first day of work:
*Be yourself
*Pay attention to your body language
*Show interest
*Learn the professional rules
*Talk to peers
*Pay attention to how decisions are made
*Listen and observe
*Don't try too hard
*Prepare your elevator pitch

16. Suppose I will be your supervisor and asked you to do something that you disagreed with, what would you do?
Answer: Interviewer trying to find out your reality when you disagreed with any supervisor so be careful while answering this and stay positive. Tell them that you will try to communicate with you and understand the both sides than only you will create any decision. Just make it clear that you are willing to do whatever needs to be done but you are a person with principles who will not hesitate to take action against anything unethical, immoral or illegal be asked of you.

17. What would you do if you will find someone in your team is not pulling their own weight?
Answer: Interviewer wants to know that how you deal with the situation where someone is not doing his best to get the job done and do you first find reason of their not working or just start scolding them. Here you need to tell your process to how you make them work effectively and i.e. :
*Ask them what's wrong
*Inspire them
*Train them
*Give them a mentor
*Give them an easier task
Example Answer : I would try and find out why first, may be they are not feeling well. Then ask how can i of help to them to get the job done.

18. Describe your performance at your last job?
Answer: Here focus on the tasks you did that will impress your interviewer, either by being relevant or showing that you have a considerable amount of intelligence. Do not gloss over this question. They may just be looking for more detail about the work that you have done. Take the requirements of the target job and show how, in the previous job, you demonstrated many of the skills and knowledge that are being sought now. Example Answer: In my last job I was working as the senior auditor, I planned and organized each visit to our client's site. I regularly trained and managed new members of our team and I was the go to person for technical auditing questions.

19. Tell me about your most significant accomplishments?
Answer: This question is about your achievements, here interviewer is trying to find out that what things you consider as you’re most significant accomplishment and why. So you need to discuss about you have accomplished at work, how you have accomplished and how much you are proud for that. Answer this with full confidence and honest. Give example of your accomplishments but be careful you don't need to brag about what you have done.

20. Tell me about all your weaknesses.
Answer: Always mention the things in weaknesses which is actually your strength at some point or about the weaknesses for which you are taking actions to improve them. You need to prepare in advance for this dreaded question. Interviewer is just trying to figure out if your weaknesses will make hard for you to do a job or fit into the organization or not. They are also checking that are you able to handle tough questions like this one. Just tell your interviewer you recognize your weaknesses and what your plans to improve upon them.