{"id":1211,"date":"2018-07-23T10:37:13","date_gmt":"2018-07-23T05:07:13","guid":{"rendered":"https:\/\/liai.co.in\/blog\/?p=100"},"modified":"2022-01-21T03:43:18","modified_gmt":"2022-01-21T03:43:18","slug":"what-is-amazon-vpc","status":"publish","type":"post","link":"https:\/\/www.liainfraservices.com\/blog\/what-is-amazon-vpc\/","title":{"rendered":"What is Amazon VPC?"},"content":{"rendered":"<\/span> 4<\/span> min read<\/span><\/span>
<\/span> 3,102<\/span><\/div>

These are the few components involved in any Amazon VPC<\/p>\n

1. Subnet
2. Route Table
3. Internet Gateway<\/p>\n

There would be one default VPC provided by AWS, which cannot be deleted. Default one can have 5 VPCs per region. One point to be remembered that VPC is an entire Region wise.<\/p>\n

When you create a VPC it creates Routing Table by default and that routing table is for internal communication of all instances in all subnets under that VPC.<\/p>\n

One VPC can have more than 1 subnet based on the Availability Zones.<\/p>\n

1 Availability Zone = 1 subnet<\/p>\n

You can configure only one internet gateway per VPC to communicate with the internet.<\/p>\n

Scenario:<\/strong><\/h3>\n

If some user has deployed an instance, and he is not able to communicate with the internet<\/p>\n

Possible situations for that would be<\/p>\n

1. Either the SG associated with that instance does not allow any outbound connection to HTTP or HTTPS.<\/p>\n

2. Maybe the instance does not have any public IP or any elastic IP associated with that.<\/p>\n

3. Most important — >  The instance is a part of the subnet which does not have any Internet Gateway associated.<\/p>\n

4. Or the route table does not have destination IP as 0.0.0.0\/0 for the Internet Gateway.<\/p>\n

Most important checks to see is \u201c Subnet \u201c and it’s \u201croute table \u201c<\/p>\n

Subnet = This will let you know if the instance is on a Private subnet (without any Internet Gateway attached to Routing Table) or Public Subnet.<\/p>\n

Route Table = This basically maintains two records Destination and Target. Here Destination means where the traffic should reach.<\/p>\n

Target means where the traffic starts.<\/p>\n

How Amazon VPC works?<\/h3>\n

Let’s take an example of a VPC which was created on a Region with two Availability Zone(AZ_1, AZ_2)<\/p>\n