AWS VPC Interview Questions

AWS VPC Interview Questions

Amazon has always been a dream company for many. Out of all the job designations, a lot of positions open up for AWS VPC developers and company look out for professionals who take up the roles and responsibilities thereby delivering results. The developers, on the other hand, have to go through an interview, which might be challenging.

AWS VPC is a commercial service by Amazon, which shall provide the users with a private virtual cloud by using a technology of OpenStack or HPE Helion Eucalyptus. The users can select their own range of IP addresses for VPC. As far as the security is concerned, the AWS VPC provides two-fold security where it uses a security group for a firewall to keep a track on the traffic at the instance level and applies network access control list to control traffic at the subnet level. The service is free of cost but if the user accesses the VPC account through VPN then it might be chargeable. Thus, the endless features and great service makes AWS VPC platform in demand.

Read Best AWS VPC Interview Questions and Answers

Given below are the top 20 AWS VPC Interview Questions that can be asked by the interview panel during the interview. All the questions listed here are answered in a manner that explains the concept clearly and is easy to understand:

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AWS VPC Interview Questions

Security groups in a VPC mention which traffic is allowed to or from an Amazon EC2 instance. Network ACLs operate at the subnet level and evaluate the traffic that is entering and exiting a subnet. Network ACLs can be used to set both Allow as well as Deny rules. Network ACLs do not filter traffic between the instances in the same subnet. Besides this, the network ACLs performs stateless filtering while security groups perform filtering.
It is good news that Amazon VPC enables the creation of an Internet gateway. This allows Amazon EC2 occurrences in the VPC to access the Internet directly. There are numerous connectivity options for my VPC.  You can connect your Virtual Private Cloud to the following:
  • Your corporate data center with the help of a Hardware Virtual Private Network connection
  • The Internet through an internet gateway
  • The Internet as well as your corporate data center, together. You can do this by using both, the virtual private gateway and the Internet gateway.
  • Other VPCs through Virtual Private Cloud Peering condition
  • Other Amazon Web Services
 In order to create and place the subnet you must be specific about the availability zone. The user can use a VPC wizard for selecting the availability for a subnet with the help of a wizard confirmation screen. The subnet can be created in a specific availability zone with the help of API or CLI. In case the user does not select a specific availability zone then automatically the default zone “No Preference” gets selected. The subnet, therefore, will get created in the zone that’s available in the region.

You can very well use your existing AMIs in Amazon VPC that is registered within the same region as your VPC.

 There are several advantages of default VPC. Firstly, if a resource is launched in default VPC, the user can avail the high-end network functions of Amazon VPC along with ease to use Amazon EC2.

Secondly, without creating a VPC or launching the instances, the user can still avail several features such as different IP address, altering the security group membership, egress filtering of the security group and several network interfaces.

 In case of stateful filtering, the point of origination of request is tracked and the reply is sent automatically to the request, which is then returned to the computer from where it originated.

In case of Stateless Filtering, it doesn’t matter whether a new request is generated or an automatic reply is sent to a request, the filter only seeks the origin or destination IP address & port.

AWS VPC better known as Amazon Virtual Private Cloud lets you furnish a logically left out department of the Amazon Web Services. Here you can launch Amazon Web Services Resources in a virtual network that is defined by you. You will have absolute control over your virtual networking environment along with the privilege of choosing your own IP address range, network gateways, the configuration of route tables and creation of subnets. You can also establish hardware VPN connection between your corporate data center as well as your VPC and influence the AWS cloud as an extension of your corporate data center.
It is available in multiple availability zones in all Amazon EC2 regions.
An Internet gateway is horizontally scaled, highly available as well as redundant. Thus, there are no bandwidth limitations for Internet gateways.
Amazon EC2 security groups are helpful to secure instances within an Amazon VPC. Security groups in VPC help you to specify both inbound as well as outbound network traffic that is allowed to and from each Amazon EC2 instance. The traffic that is not explicitly allowed to or from an instance is automatically denied.
 If a user’s AWS account has been created after March then it can launch default VPC resources. If an account has been created before March then it shall use any default VPC in any region specific to that. The region should not have a previous launch or any provision related to Amazon RDS, Amazon Redshift resources etc.
The Amazon VPC contains various elements:
  • VPC- a logically secluded virtual network in the Amazon Web Services cloud. You only need to define a Virtual Private Cloud’s IP address space from the range that you select
  • Internet Gateway- Internet Gateway is the Amazon VPC’s side of a connection to the public internet
  • Subnet- Subnet is a part of cloud’s IP address space from the range that you select
  • NAT Gateway- A highly available and managed NAT service for your resources in a private subnet to use the internet
  • Virtual Private Gateway- This is the Amazon VPC’s side of a VPN connection
  • Customer Gateway- It is the user’s side of a VPN connection
  • Router- Routers interconnect subnets and the direct traffic between Virtual Private Gateways, Internet Gateways, NAT gateways as well as subnets.

When Amazon EC2 instance is launched you must specify the subnet in which to launch the instance. This instance will be then launched in the availability zone that is associated with the given subnet.

In order to build a custom VPC, the following steps must be followed:
  • Create a Virtual Private Cloud
  • Then create Subnets
  • Further create an Internet Gateway
  • Attach this new Gateway to your VPC
  • Create a new Route Table
  • Add the gateway as a route to the new route table
  • Add a subnet to the route table’s subnet association
  • Create a web server for public subnet and a database server for the private subnet
  • Create a new security group for the NAT
  • Add HTTP and HTTPS inbound rules that let in traffic from the private subnets IP
  • Create a NAT for public subnet
  • Create an elastic IP
  • Associate this IP to the NAT
  • Disable destination/source checks for the NAT
  •  Add NAT to the initial VPC route table as a route.