Dynamic NAT
In dynamic NAT, the router dynamically maps inside local addresses to inside global addresses as needed.
An ACL is used to identify which traffic should be translated.
If the source IP is permitted by the ACL, the source IP will be translated.
If the source IP is denied by the ACL, the source IP will not be translated.
It will not be dropped.
A NAT pool is used to define the available inside global addresses.
Although they are dynamically assigned, the mappings are still one-to-one (one inside local IP address per inside global IP address).
If there aren't enough inside global IP addresses available (= all currently being used), it is called 'NAT pool exhaustion'.
If a packet from another inside host arrives and needs NAT but there are no available addresses, the router will drop the packet.
The host will be unable to access outside networks until one of the inside global IP addresses becomes available.
Dynamic NAT entries will time out automatically if not used, or you can clear them manually.
NAT pool exhaustion
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