9 Feb 2016

Amazon VPC

Virtual Private Cloud




1. Like your Virtual Data Center.

2. VPC lets you provision a logically isolated section of AWS, where you can launch AWS resources in a

     virtual network you define.

3. Will have complete control on NW environment, like own IP range, creation of subnets,

      configuration of route tables and network gateways, internet gateways attach to subnets.

4. Can leverage multiple layers of security, including security groups and network access control lists to control

    EC2 instances in each subnet.

5. Can create hardware VPN between corporate DataCenter and AWS VPC.

6.  Can launch instances of subnet.

7. 2 levels of security groups

      a. instance security groups

       b. subnet network access contols (ACLS)

8. Default VPC and Custom VPC

    Default vpc:

        a. user friendly, immediately deploy instances.

       b. All subnets has internet gateways

       c. EC2 instance has both public and private IP address

      d. once you delete default VPC only AWS can help.

  Custom VPC


9. VPC Peering

       a. allows to connect 1VPC with other via direct network route using private IP address.

     b. can peer VPC with other AWS account as well as other VPCs in same account.

     c. Peering is in a start configuration  1central VPC peers with 4 others.


10. VPC Restriction

  1. 5 elastic IP address.

2. 5 Internet Gateways

3. 5 VPCs per regions

4. 50 VPN connections per region.

5. 50 customer Gateways per region.

6. 200 Route Tables per region.

7. 100 Security Groups per VPC.

8. 50 Rules per Security group.

Differences between Entities and Value Object.


When you have two Entities with the same attributes, these two objects are not the same because they have two different identities.

However, when you have two Value Objects with the same values, these two objects do have equality and can therefore can be interchanged freely. When you can substitute one object for another, the object is a Value object (in other words, the value is in the object, rather than the identity of the object). You couldn’t interchange Entities because there would be unwanted side effects.


2. Overtime an Entity’s properties will change, but it will remain the same Entity. For example, if a user changes their email address. However when your application needs to change a Value Object property, the whole object needs to be destroyed and a new one should replace it. For example, when you make a payment, the money object isn’t given back to you as change, you are given a new money object of a lower value.