Hi @VengadeshB52217,
Postman is simply an API development and testing tool. It can be used online and for free.... it simply allows you to test whether the the API you have works outside of ServiceNow.
This will help isolating where the issue could be.
On the basis you're getting a '0' response code, you need to speak to the team who look after the Jira and or the network team so you can access the API.
Putting the attachment side, can you post and create a ticket without an attachment?
To help others (and for me to gain recognition for my efforts), please mark this response correct by clicking on Accept as Solution and/or Kudos.
Thanks, Robbie
