Default security group behavior in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a default security group in AWS?

A default security group is automatically created for each VPC. It controls inbound and outbound traffic for instances without a custom security group.

beginner

What inbound traffic rules does the default security group have?

It allows inbound traffic from instances assigned to the same security group, meaning instances can communicate with each other by default.

beginner

What outbound traffic rules does the default security group have?

It allows all outbound traffic to any destination by default, so instances can send traffic anywhere unless restricted.

intermediate

Can you delete the default security group in a VPC?

No, the default security group cannot be deleted. It always exists to ensure basic network security.

intermediate

Why is it important to understand the default security group behavior?

Because it affects how instances communicate by default and helps avoid unintended open access or blocked traffic.

What does the default security group allow for inbound traffic?

A Traffic from instances assigned to the same security group

B All inbound traffic from the internet

C No inbound traffic by default

D Only SSH traffic

The default security group allows inbound traffic only from instances assigned to the same security group.

Can you delete the default security group in an AWS VPC?

A Yes, anytime

B No, it cannot be deleted

C Only via AWS Support

D Only if no instances use it

The default security group cannot be deleted; it always exists in the VPC.

What is the default outbound rule of the default security group?

A No outbound traffic allowed

B Outbound traffic allowed only to the same security group

C All outbound traffic allowed

D Outbound traffic allowed only on port 80

By default, the default security group allows all outbound traffic.

Why might you want to modify the default security group?

A To restrict traffic between instances for security

B To allow all inbound traffic from the internet

C To delete it and create a new one

D To disable outbound traffic permanently

Modifying the default security group can help restrict traffic between instances to improve security.

Which statement about the default security group is true?

A It blocks all traffic by default

B It allows inbound traffic from any IP address

C It is deleted when you create a new VPC

D It allows inbound traffic only from instances in the same group

The default security group allows inbound traffic only from instances assigned to the same security group.

Explain the default inbound and outbound rules of the AWS default security group and why they matter.

Think about how instances talk to each other by default.

Describe what happens if you do not assign a custom security group to an EC2 instance in a VPC.

Consider the default network access the instance gets.