SRX does not require Source and Destination NAT to handle the traffic. SRX is smart to use the session created to handle the traffic on both ways

• SRX configured with Source and Destination NAT:
• Dropping many traffic
• Traffic which was able to get out to internet is not getting translated.

You will need to choose NAT based on the requirements of the network.

If traffic is generated outside the network it will be recommended to use destination NAT.

If traffic is generated inside the network it will be recommended to use source NAT.

In case Destination NAT is selected, please make sure to configure from-zone to-zone policy is addressing the source address to the IP already translated by NAT; otherwise, traffic will be dropped.

Source NAT

Destination NAT

Static NAT