Create a vpc for ntier

• Basic ntier architecture with high availability and fault tolerance
  
• In AWS we have Regions and Zones
  • subnets are scoped to Zones
• The AWS VPC with subnets
  
  
• In this vpc we have a default route table
  
• All the internal communications with in vpc is allowed
  
• With every vpc created we get a default
  • security group
    
  • network acl
    
• Lets create an ec2 instance in web1 subnet
  
  
• To connect to this ec2 instance from outside lets use

ssh -i <path to pem> ubuntu@<public-ip>

* This will not work as vpc doesnot have internet connectivity.

* Lets create internet gateway and attach this to vpc





* Now enable route between route table and internet gateway.
* Navigate to route table then routes




* Lets try to connect ssh from laptop again



* Lets look at network interface which is called as elastic network interface by aws

* Security Group is attached to network interface which allows only the packets with entries written in security group