Exam NSE4_FGT_AD-7.6 Topic 1 Question 138 Discussion

From the exhibits:
The firewall policy has NAT enabled and is configured to Use Dynamic IP Pool.
The selected IP pool (Internet-pool) is configured as:
Type: One-to-One
External IP Range: 100.65.0.110-100.65.0.111 (only two public IPs)
PC1 and PC2 can access the internet because each one-to-one NAT mapping consumes one public IP from the pool. When PC3 is added, there is no third public IP available in the pool, so FortiGate cannot allocate a one-to-one mapping for PC3 and the session fails.
FortiOS behavior here is standard: with one-to-one IP pools, the available pool size limits how many distinct internal sources can be translated concurrently (depending on allocation and sessions), and a pool with only two IPs will not reliably support three separate hosts needing translations.
Therefore, the administrator can fix this in two valid ways:
B . In the IP pool configuration, set end ip to 100.65.0.112.
This expands the pool by adding an additional public IP address, making three public IPs available (.110, .111, .112), so PC3 can be assigned an address for one-to-one NAT.
D . In the IP pool configuration, set type to overload.
Changing the pool type to overload enables PAT (many-to-one), allowing multiple internal hosts (PC1, PC2, PC3) to share the pool address(es) using different source ports. This removes the "one public IP per internal host" limitation inherent to one-to-one pools.
Why the other options are not correct:
A . Multiple Interface Policies is unrelated to IP pool exhaustion and does not solve NAT allocation limits.
C . match-vip affects VIP matching behavior for destination NAT/virtual IP usage and does not address the source NAT pool shortage causing PC3 to fail.