The number of concurrent Secure Connect user licenses that an SRX Series device has by default is 2. Secure Connect is a feature of Juniper SRX Series devices that allows you to securely connect to remote networks via IPsec VPN tunnels. Each SRX Series device comes with two concurrent Secure Connect user licenses by default, meaning that it can support up to two simultaneous IPsec VPN connections. For more information, please refer to the Juniper Networks SRX Series Services Gateways Security Configuration Guide, which can be found on Juniper's website.

The main purpose of using screens on an SRX Series device is to provide protection against common Denial of Service (DoS) attacks. Screens help prevent network resources from being exhausted or unavailable by filtering or blocking network traffic based on predefined rules. The screens are implemented as part of the firewall function on the SRX Series device, and they help protect against various types of DoS attacks, such as TCP SYN floods, ICMP floods, and UDP floods.