Networking Flashcards
VPC
Virtual Private Cloud
Imagine the millions of customers who use AWS services. Also, imagine the millions of resources that these customers have created, such as Amazon EC2 instances. Without boundaries around all of these resources, network traffic would be able to flow between them unrestricted.
A networking service that you can use to establish boundaries around your AWS resources is Amazon Virtual Private Cloud (Amazon VPC)(opens in a new tab).
Amazon VPC enables you to provision an isolated section of the AWS Cloud. In this isolated section, you can launch resources in a virtual network that you define. Within a virtual private cloud (VPC), you can organize your resources into subnets.
Subnets
A subnet is a section of a VPC that can contain resources such as Amazon EC2 instances. A subnet is a section of a VPC in which you can group resources based on security or operational needs. Subnets can be public or private.
Internet Gateway
To allow public traffic from the internet to access your VPC, you attach an internet gateway to the VPC.
An internet gateway is a connection between a VPC and the internet. You can think of an internet gateway as being similar to a doorway that customers use to enter the coffee shop. Without an internet gateway, no one can access the resources within your VPC.
Virtual Private Gateway
The virtual private gateway is the component that allows protected internet traffic to enter into the VPC. Even though your connection to the coffee shop has extra protection, traffic jams are possible because you’re using the same road as other customers.
A virtual private gateway enables you to establish a virtual private network (VPN) connection between your VPC and a private network, such as an on-premises data center or internal corporate network. A virtual private gateway allows traffic into the VPC only if it is coming from an approved network.
AWS Direct Connect
AWS Direct Connect(opens in a new tab) is a service that lets you to establish a dedicated private connection between your data center and a VPC.
The private connection that AWS Direct Connect provides helps you to reduce network costs and increase the amount of bandwidth that can travel through your network.
Network ACL
Network Access Control List: The VPC component that checks packet permissions for subnets. A network ACL is a virtual firewall that controls inbound and outbound traffic at the subnet level.
Network ACLs perform stateless packet filtering. They remember nothing and check packets that cross the subnet border each way: inbound and outbound.
Public subnet
Public subnets contain resources that need to be accessible by the public, such as an online store’s website.
Private subnet
Private subnets contain resources that should be accessible only through your private network, such as a database that contains customers’ personal information and order histories.
Packet
A packet is a unit of data sent over the internet or a network. It enters into a VPC through an internet gateway. Before a packet can enter into a subnet or exit from a subnet, it checks for permissions. These permissions indicate who sent the packet and how the packet is trying to communicate with the resources in a subnet.
Security Group
A security group is a virtual firewall that controls inbound and outbound traffic for an Amazon EC2 instance.
Security group firewall protecting an Amazon EC2 instance.
By default, a security group denies all inbound traffic and allows all outbound traffic. You can add custom rules to configure which traffic should be allowed; any other traffic would then be denied.
Security groups perform stateful packet filtering. They remember previous decisions made for incoming packets.
DNS
Domain Name System
Amazon Route 53
Amazon Route 53 is a DNS web service. It gives developers and businesses a reliable way to route end users to internet applications hosted in AWS.
Amazon Route 53 connects user requests to infrastructure running in AWS (such as Amazon EC2 instances and load balancers). It can route users to infrastructure outside of AWS.
Another feature of Route 53 is the ability to manage the DNS records for domain names. You can register new domain names directly in Route 53. You can also transfer DNS records for existing domain names managed by other domain registrars. This enables you to manage all of your domain names within a single location.
