# Optional Steps
## Task 1: Troubleshooting connectivity between the private instance and the public instance
In this optional task, you use the Internet Control Message Protocol (ICMP) to validate a private instance’s network reachability from the public instance.
**Note:** This task is **optional** and is provided in case you have lab time remaining. You can complete this task or skip to the [end](https://us-east-1.durian.bkr.team.aws.training/session/8EbsdpwLaNcZeZgYjmdzvr?locale=en-US&reference=wDd9KFmKCDK2x8tifh4WFu%3A%3A44f534f1-7b32-464b-88da-8df283f68842#conclusion) of the lab.
134. Return to the AWS Management Console browser tab.
135. In the left navigation pane, choose **Instances**.
136. Select **Private Instance**.
137. On the **Details** tab, copy the value of **Private IPv4 addresses** to your clipboard.
**Note:** To copy the private IPv4 address, hover over it and choose the copy icon.
138. Unselect **Private Instance**.
139. Select **Public Instance**.
140. Choose Connect.
The **Connect to instance** page is displayed.
141. Choose the **Session Manager** tab.
142. Choose Connect.
A new browser tab or window opens with a connection to the **Public Instance**.
First, use a *curl* command to retrieve a header file and confirm is the web app hosted on the private instance is reachable from the public instance.
143. **Command:** Copy the following command to your notepad. Replace **PRIVATE\_IP** with the value of the **Private IPv4 address** for the **Private Instance**:
```
curl PRIVATE_IP
```
**Expected output:**
```
It works!
```
144. **Command:** Copy the following command to your notepad. Replace **PRIVATE\_IP** with the value of the **Private IPv4 address** for the **Private Instance**:
```
ping PRIVATE_IP
```
145. **Command:** Copy and paste the updated command in your terminal and press **Enter**.
**This is a sample command only.** Do not use the following command.
```
ping 10.0.2.131
```
146. After a few seconds, stop the ICMP ping request by pressing CTRL+C.
**The ping request to the private instance fails**. Your challenge is to use the console and figure out the correct *inbound rule* required in the **Private SG** to be able to successfully ping the private instance.
If you have trouble completing the optional task, refer to the [Optional Task Solution](https://us-east-1.durian.bkr.team.aws.training/session/8EbsdpwLaNcZeZgYjmdzvr?locale=en-US&reference=wDd9KFmKCDK2x8tifh4WFu%3A%3A44f534f1-7b32-464b-88da-8df283f68842#optional-solution) section at the end of the lab.
---
## Task 2: Retrieving instance metadata
In this optional task, you run instance metadata commands on AWS CLI using a tool such as cURL. Instance metadata is available from your running Amazon EC2 instance. This can be helpful when you write scripts to run from your Amazon EC2 instance.
**Note:** This task is **optional** and is provided in case you have lab time remaining. You can complete this task or skip to the [end](https://us-east-1.durian.bkr.team.aws.training/session/8EbsdpwLaNcZeZgYjmdzvr?locale=en-US&reference=wDd9KFmKCDK2x8tifh4WFu%3A%3A44f534f1-7b32-464b-88da-8df283f68842#conclusion) of the lab .
147. Return to the browser tab with the AWS Management Console open.
148. In the left navigation pane, choose **Instances**.
149. Select **Public Instance**.
150. Choose Connect.
The **Connect to instance** page is displayed.
151. Choose the **Session Manager** tab.
152. Choose Connect.
A new browser tab or window opens with a connection to the **Public Instance**.
153. **Command:** To view all categories of instance metadata from within a running instance, run the following command:
```
TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` \
&& curl -H "X-aws-ec2-metadata-token: $TOKEN" -v http://169.254.169.254/latest/meta-data/
```
154. **Command:** Run the following command to retrieve the public-hostname (one of the top-level metadata items that were obtained in the preceding command):
```
curl -H "X-aws-ec2-metadata-token: $TOKEN" -v http://169.254.169.254/latest/meta-data/public-hostname
```
**Note:** The IP address 169.254.169.254 is a link-local address and is valid only from the instance.
You have successfully learned how to retrieve instance metadata from your running Amazon EC2 instance.