What Happens When You Reboot An Ec2 Instance

Operating Systems

When it comes to managing cloud infrastructure, one of the most common tasks is rebooting an EC2 instance. As an expert in technical topics, I am excited to share with you the process and what actually happens when you reboot an EC2 instance.

First of all, let me explain what an EC2 instance is. EC2 stands for Elastic Compute Cloud, and it is a virtual machine provided by Amazon Web Services (AWS). It allows you to run applications on a virtual server in the cloud. Rebooting an EC2 instance means restarting or refreshing the virtual server, similar to how you would reboot your computer.

When you initiate a reboot of an EC2 instance, the following steps take place:

Step 1: Graceful Shutdown

Before the actual reboot process begins, the operating system running on the EC2 instance performs a graceful shutdown. This ensures that any running applications or processes have a chance to clean up and save their state properly. In some cases, the operating system may even trigger an automatic restart of any essential services to ensure a smooth transition.

Step 2: Stop and Start

Once the EC2 instance has gracefully shut down, AWS performs a stop and start operation. This means that the instance is effectively stopped and then started again. During this process, the hypervisor reassigns the instance to a new underlying physical host while keeping the same instance ID, public IP address, and other configuration details intact.

It’s worth noting that the stop and start operation differs from a simple restart. When you restart an EC2 instance, AWS performs a soft reboot, similar to a restart on your personal computer. On the other hand, a stop and start operation is more like a clean shutdown and boot-up process.

Step 3: Network Configuration

After the stop and start operation, the network configuration of the EC2 instance is re-established. This includes assigning the same Elastic Network Interface (ENI) and associated IP addresses to the instance. It ensures that any public or private IP addresses assigned to the instance remain unchanged after the reboot.

Step 4: Reboot Complete

Once the network configuration is complete, the EC2 instance is considered rebooted. Any applications or services running on the instance will start up again, similar to a fresh boot-up. You can then access the instance and resume your work as usual.

Overall, rebooting an EC2 instance is a crucial task for maintaining the health and performance of your cloud infrastructure. It allows you to refresh the instance, close any lingering processes, and resolve certain issues that may arise. It’s a simple yet powerful tool in your arsenal when it comes to managing your EC2 instances.


In conclusion, rebooting an EC2 instance involves a graceful shutdown, a stop and start operation, network configuration, and finally, a complete reboot. It’s a necessary process for maintaining the health and stability of your cloud infrastructure. Whether you need to apply updates, troubleshoot issues, or simply refresh the instance, rebooting an EC2 instance is a straightforward and effective solution.