The proper placement of an ACL can make the network operate more efficiently. An ACL can be placed to reduce unnecessary traffic. For example, traffic that will be denied at a remote destination should not be forwarded using network resources along the route to that destination.

Every ACL should be placed where it has the greatest impact on efficiency. As shown in the figure, the basic rules are:

Placement of the ACL and therefore the type of ACL used may also depend on:

Note: For CCNA certification the general rule is that extended ACLs are placed as close as possible to the source and standard ACLs are placed as close as possible to the destination.