PCNSA · Question #310
Which two matching criteria are used when creating a Security policy involving NAT? (Choose two.)
The correct answer is A. Pre-NAT address D. Post-NAT zone. When creating a security policy involving NAT, the firewall uses the Pre-NAT address as the source matching criterion and the Post-NAT zone as the destination zone matching criterion.
Question
Which two matching criteria are used when creating a Security policy involving NAT? (Choose two.)
Options
- APre-NAT address
- BPost-NAT address
- CPre-NAT zone
- DPost-NAT zone
How the community answered
(24 responses)- A92% (22)
- B4% (1)
- C4% (1)
Why each option
When creating a security policy involving NAT, the firewall uses the Pre-NAT address as the source matching criterion and the Post-NAT zone as the destination zone matching criterion.
Security policies are evaluated on the original (Pre-NAT) source IP address, as this represents the true identity of the initiator before any address translation occurs.
Security policies are not matched on the post-NAT address, whether source or destination, because the policy engine needs to make decisions based on the packet's original source and its intended logical destination zone after translation.
Security policies use the source zone based on the original ingress interface, but for destination-based NAT, the destination zone is evaluated based on where the packet is intended to go *after* NAT, which is the post-NAT zone, not a pre-NAT zone.
For destination NAT (DNAT), the security policy applies to the post-NAT destination zone because the packet is routed to that zone after its destination IP address is translated.
Concept tested: Security policy matching with NAT
Source: https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/nat/nat-policy/nat-rule-behavior-and-the-security-policy.html
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