CompTIA Security+ Question E-63

A database administrator contacts a security administrator to request firewall changes for a connection to a new internal application. The security administrator notices that the new application uses a port typically monopolized by a virus. The security administrator denies the request and suggests a new port or service be used to complete the application’s task. Which of the following is the security administrator practicing in this example?

A. Explicit deny
B. Port security
C. Access control lists
D. Implicit deny

Answer: C

Traffic that comes into the router is compared to ACL entries based on the order that the entries occur in the router. New statements are added to the end of the list. The router continues to look until it has a match. If no matches are found when the router reaches the end of the list, the traffic is denied. For this reason, you should have the frequently hit entries at the top of the list. There is an implied deny for traffic that is not permitted.