As you may be aware, new PCI DSS requirements state that all payment systems must disable early TLS by 2018.
As part of this requirement, PayPal, Auth.Net and Braintree are updating its services to require TLS 1.2 for all HTTPS connections along with requiring HTTP/1.1 for all connections. You need to make sure your CiviCRM is all set with this change which you could do by doing the following checks.