Securing EC2 Instances in a Custom VPC

Answer - A

Option A is correct because we need to specify the allowed traffic in the security group, i.e., HTTP and HTTPS Traffic must be allowed from all sources.No inbound traffic is allowed by default.

By adding security group rules, you can specify which traffic you want to allow.

This is essentially a whitelist.

Options B is incorrect since, by default, nothing is allowed, and in the Security group, we can't specify what is denied.

We don't have any deny option in Security Groups.

Option C is incorrect because we can specify what is allowed in the security group but not what is denied.

If you want to deny explicitly, you should use the Network Access control list.

Option D is incorrect since this would be a security issue.

For more information on VPC Security groups, please refer to the below URL-

https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html

The correct answer is A. Add a security group rule to allow HTTP and HTTPS Traffic.

Explanation:

A security group acts as a virtual firewall that controls the traffic for one or more instances. It allows you to specify inbound and outbound traffic to your instances.

To allow only HTTP and HTTPS traffic into the instance, we need to add a security group rule that allows inbound traffic on ports 80 (HTTP) and 443 (HTTPS).

Option A is the correct answer because it allows only the necessary traffic, HTTP and HTTPS, and denies all other traffic.

Option B is incorrect because it explicitly denies all traffic before allowing HTTP and HTTPS, which means that no other traffic can be allowed even if it is necessary.

Option C is also incorrect because it denies all explicit traffic on HTTP and HTTPS, which means that even the necessary traffic for the web application would be denied.

Option D is incorrect because it allows all traffic, including unnecessary and potentially harmful traffic.

Therefore, the correct approach is to add a security group rule that allows HTTP and HTTPS traffic.