Cisco Certified Network Associate (CCNA) Practice Exam

What keyword is used to permit or deny traffic in an ACL?

1. allow

2. grant

3. permit

4. admit

The correct answer is: permit

The keyword "permit" is used in Access Control Lists (ACLs) to explicitly allow traffic to pass through a network device, such as a router or switch. When configuring ACLs, network administrators define rules that control the flow of traffic based on parameters like IP addresses, protocols, or port numbers. Using "permit" in an ACL entry indicates that traffic matching the conditions specified in that rule is allowed to traverse the interface where the ACL is applied. For example, if you use a rule like "permit ip 192.168.1.0 0.0.0.255" in an ACL, you are allowing all IP traffic from the specified subnet to proceed through the network device. Understanding this concept is pivotal in managing network security and performance, as it helps to control which packets are processed and forwarded, thereby helping to prevent unauthorized access while enabling legitimate traffic. The other options do not reflect the correct terminology used in ACL configurations. For instance, "allow," "grant," and "admit" are not recognized keywords in Cisco IOS for defining rules within ACLs, which is why "permit" is the appropriate choice.