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Cisco CCNA Security Training: The access-list dynamic-extend command 

Added: 08/13/2009, Hits: 6,294, Rating: 0, Comments: 0, Votes: 0
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In today’s article, I’m going to quickly inform you about the Cisco IOS Global configuration command named “access-list dynamic-extend”.

Network administrators (like you) use the “access-list dynamic-extend” to allow the absolute timer of the dynamic access control list (ACL) to be extended an additional six minutes.

In other words, after you’ve enabled the lock-and-key function by using the access-enable command and attempt to create a Telnet session to the router to re-authenticate yourself; you can use “access-list dynamic-extend” command to extend the absolute timer of the dynamic ACL by six minutes.

Note: If you need to use the command, make sure you implement it before the ACL expires.

Below is the command’s syntax:

access-list dynamic-extend

As you can see, the command is really easy to use; it doesn’t have any keywords or arguments.

And, here’s an example of the command being typed on a router.

Router#configure terminal
Router(config)#access-list dynamic-extend
Router#copy run start

In the example above, the router is being configured with the command.

And, like with mostly all Cisco IOS commands; you can use the word “no” in front of the command to remove (disable) the configured command; like you see below:

Router(config)#no access-list dynamic-extend

By the way, if you decide to use the command, make sure your router(s) is running Cisco IOS 12.1(5)T or higher.

I hope this article was very informative and helped you quickly understand the usage of the access-list dynamic-extend command. If you need to learn more; I suggest you visit my website, ( were you’ll find the latest information regarding the Cisco CCNA (640-553) Security exam techniques.

To your success,

Charles Ross
CCNA- CCNP #CSCO10444244

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