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NATPrivileged EXEC

clear ip nat translation *

Clears all dynamic NAT translations from the translation table, forcing the router to rebuild translations for new traffic.

Syntax·Privileged EXEC
clear ip nat translation *

When to Use This Command

  • After changing NAT configuration (e.g., ACL, pool, or overload rules) to apply changes immediately without reloading.
  • When troubleshooting connectivity issues caused by stale or incorrect NAT entries.
  • Before testing new NAT policies to ensure a clean state for verification.
  • When a NAT pool is exhausted and you need to free up entries for new sessions.

Command Examples

Clear all dynamic NAT translations

clear ip nat translation *
Router#
Router#

No output is displayed upon successful execution. The command silently clears all dynamic translations. Use 'show ip nat translations' to verify that the table is empty.

Verify cleared translations

show ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
--- ---                 ---                ---                ---

Router#

After clearing, the translation table shows only headers with no entries, confirming all dynamic translations have been removed.

Understanding the Output

The 'clear ip nat translation *' command produces no output on success. To verify, use 'show ip nat translations'. The output of that command has columns: Pro (protocol, e.g., tcp, udp, icmp), Inside global (public IP:port), Inside local (private IP:port), Outside local (destination IP:port as seen from inside), Outside global (destination IP:port as seen from outside). An empty table (no entries) confirms all dynamic translations are cleared. Static NAT entries are not affected. If translations remain, they may be static or the clear command was not executed in privileged EXEC mode.

CCNA Exam Tips

1.

Remember that 'clear ip nat translation *' only clears dynamic entries; static NAT entries remain untouched.

2.

The command requires privileged EXEC mode (enable) — a common exam trick is to test if you know the mode.

3.

On the CCNA exam, you may be asked to clear translations after modifying an ACL used by NAT; this command applies the change immediately.

4.

Be aware that clearing translations can disrupt active sessions; the exam may test your understanding of when it is appropriate.

Common Mistakes

Using the command in user EXEC mode (>) instead of privileged EXEC mode (#), resulting in '% Invalid input detected'.

Confusing 'clear ip nat translation *' with 'clear ip nat translation inside/outside' which clears specific entries.

Forgetting that clearing translations does not affect the NAT configuration itself; only the active translation table is cleared.

Related Commands

show ip nat statistics

Displays statistics about NAT translations, including active translations, hit counts, and configuration parameters, used to verify NAT operation and troubleshoot translation issues.

show ip nat translations

Displays the current active Network Address Translation (NAT) translations on the router, used to verify NAT operations and troubleshoot connectivity issues.

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