What is Virtual Private Cloud (VPC)?

Amazon Virtual Private Cloud (Amazon VPC) enables you to launch AWS resources into a virtual network that you have defined.
In Amazon Web Services or virtual private cloud, or VPC is a virtual network definition that contains subnets among other things, into which you can deploy resources like EC2 instances.
Your VPC supports both IPv4 and IPv6 addressing. CIDR, C-I-D-R, stands for Classless Inter-Domain Routing.
So for example, 192.168.1.0 is a network address. Here we’ve got /24, so the first 24 bits starting from the left are the network bits. In this case that means 192.168.1 identifies the network.

Explain VPC Configuration Items.

When you configure a VPC, there are a number of items that you need to be aware of.
First of all, VPCs contain subnets. Those subnets are what actually contain resources such as EC2 instances.

You can also configure DHCP options for your VPC. Now, you might want to control for instance, the DNS domain suffix that’s applied to instances.
You might want to specify the IP addresses of custom DNS servers, and so on. You can also configure the network ACL.

A network ACL is essentially a list of inbound and outbound firewall rules at the subnet level. So within a network ACL, you can configure both allow and deny rules.
You can also configure a route table at the VPC level. The route table contains routing table entries, if you want to control network traffic flow.
You can also assign tags. Tags are metadata or key and value pairs that describe a resource in AWS.

Within a VPC by default, DNS name resolution is enabled. You can configure a DHCP options set if you really want to use custom DNS servers.
DNS host names are enabled by default.