unable to access https://www.irctc.co.in/ from lightsail

Based on the information provided and the error message shown in your screenshots, it appears that you're experiencing a DNS resolution issue when trying to access https://www.irctc.co.in/ from your Lightsail instance. The error "curl: (6) Could not resolve host: www.irctc.co.in" indicates that the DNS lookup for the domain name is failing.

This issue is not related to firewall rules, as firewall configurations control incoming traffic to your instance rather than outgoing requests. Since you haven't configured any firewall rules yet, this further confirms that the problem lies elsewhere.

To troubleshoot this issue:

1. First, check if the DNS resolution problem is specific to this website or if it's a general issue. Try accessing other websites or running nslookup commands for different domain names to see if they resolve correctly.

2. Verify that your Lightsail instance has proper network connectivity. Ensure that the network adapter is correctly attached and functioning.

3. Check the DNS configuration on your Lightsail instance. Make sure it's set to use valid DNS servers. You can typically find this in the /etc/resolv.conf file on Linux instances.

4. If the issue persists, you may want to try restarting your Lightsail instance. Sometimes, a simple restart can resolve network-related issues.

5. If none of the above steps work, you might want to consider creating a snapshot of your instance and restoring it to a new instance. This will create a fresh instance with the same configuration but potentially resolve any underlying network issues.

Remember, this appears to be a DNS resolution problem rather than a firewall issue. If the problem continues after trying these steps, you may need to contact AWS support for further assistance with your Lightsail instance's network configuration.
Sources
Troubleshoot website access errors on Lightsail | AWS re:Post
Cannot connect to my AWS Lightsail server | AWS re:Post

for other domains it is fine, It is a fresh instance that i created today. I have not made any changes to it.

Here is the output of nslookup and ping

Hello.

I think the problem is with "https://www.irctc.co.in/" since it can be displayed without any problem on other websites.
Is "https://www.irctc.co.in/" a site you manage?
In that case, please check whether the connection from Lightsail is blocked by a firewall, etc.