How many security groups can you associate with an Amazon Elastic Compute Cloud (EC2) instance?

An EC2 instance can be associated with multiple security groups at the same time, which allows for greater flexibility in managing the network access rules. By using multiple security groups, you can effectively aggregate permissions from different groups tailored for various functionalities or roles. For instance, one security group might allow web traffic, while another might permit SSH access, and associating both with the same instance enables it to receive traffic according to the combined rules of these groups.

This arrangement enhances the ability to secure instances while also allowing instances to belong to different sets of rules without the need to create a new security group for every specific use case. Thus, associating more than one security group with an EC2 instance is essential for leveraging AWS's robust security configurations effectively. This approach provides a granular level of control over your instance's inbound and outbound traffic.