A network engineer on router R1 configures dynamic Network Address Translation using an IP pool containing two public addresses ( to ) to service the internal subnet . Access Control List 10 permits traffic from . The router configuration includes the statement `ip nat inside source list 10 pool NAT_POOL`. During peak operating hours, users report that after two simultaneous connections are established, all additional internal hosts fail to reach external destinations. Output from `show ip nat statistics` displays active translations at maximum pool capacity with zero port translation entries. Which configuration change will allow all internal hosts to share the public addresses concurrently?
- Append the `overload` keyword to the `ip nat inside source list 10 pool NAT_POOL` command.Answer
- BModify Access Control List 10 to permit source traffic from to match public routing tables.
- CAdd a standard Access Control List statement with `permit any` at the beginning of ACL 10 to bypass pool tracking.
- DReassign the `ip nat inside` directive to the WAN interface and `ip nat outside` to the LAN interface.
Answer
Append the `overload` keyword to the `ip nat inside source list 10 pool NAT_POOL` command to enable Port Address Translation (PAT).
The command `ip nat inside source list 10 pool NAT_POOL` without the `overload` keyword performs dynamic 1-to-1 NAT mapping. With only two IP addresses in the pool, only the first two internal hosts receive translations; all subsequent translation attempts fail once the pool is exhausted. Appending the `overload` keyword activates Port Address Translation (PAT), allowing thousands of connections from internal hosts to share the pool IP addresses by tracking unique L4 transport port numbers.
Step-by-Step Solution
Key Concept
Port Address Translation (PAT) vs. Dynamic 1-to-1 NAT