What is a aws vpc?
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A VPC - Virtual Private Cloud, is a virtual network which can be segregated for creating AWS resources within it. It is isolated from other virtual networks. You can have multiple VPC.
VPC is assigned to one AWS region, but the VPC can span multiple availability zones within that region.
Security layer is added to VPC by way of Security Groups (SG's)
Used for simple website, multi-tier application, & scalable web application.
Use CIDR blocks of private network ranges for VPCs.
- 10.0.0.0 - 10.255.255.255 (10/8 prefix)
- 172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
- 192.168.0.0 - 192.168.255.255 (192.168/16)
Assign one CIDR block per VPC, the allowed block size is between /16 and /28, and IPv6 addressing can also be used, but must have IPv4 addressing as well.
The size of the VPC network addressing cannot be modified once created.
Default VPC
See http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/default-vpc.html for more information.
An AWS account comes with a default VPC, it's ready to use, has /16 CIDR block, it has one AZ, with one subnet.
- All subnets are public and associated with the main routing table, a rule which routes all traffic configured for the internet to go to the Internet Gateway (IGW).
- Any EC2 Instance launched in the default VPC receive public & private IPv4 network addresses.
- EC2 Instances also receive public & private DNS hostnames.
- The default VPC has a default security group.
- The default VPC has a default Network ACLs.
- The default VPC has a default DHCP configuration associated with it.
- If the default VPC is deleted the only way set a new default VPC, is via a support ticket to AWS, you set a VPC as the default VPC yourself.
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