From the course: Cisco CCNP Enterprise: ENARSI (300-410) Cert Prep

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IPv4 access control lists (ACLs)

IPv4 access control lists (ACLs)

- [Instructor] Access Control Lists are one of the most commonly used features in iOS, we can use those for traffic filtering for route redistribution, packet identification for policy based routing, and much more. So it's important to be able to interpret and troubleshoot those. That's what we're going to examine here. Specifically, look at troubleshooting IP version 4 access control lists used for traffic filtering. A few key things you want to remember about ACLs when troubleshooting are first ACLs are processed in a top down manner, they are made up of multiple access control entries, or ACEs and the order of these ACEs does matter. Entries are processed in order from top to bottom. Also, remember that when a packet arrives, the first ACE that matches the packet values which are being examined, will be applied, and the processing will stop. So if a packet matches multiple entries in the ACL, the only action that's…

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