Which of the following is best practice to put at the end of an ACL?

A.
Implicit deny

B.
Time of day restrictions

C.
Implicit allow

D.
SNMP string

Explanation:
An implicit deny clause is implied at the end of each ACL. This implies that if you aren’t specifically granted access or privileges for a resource, you’re denied
access by default. The implicit deny clause is set by the system.
Incorrect Answers:
B: Time of day restrictions limit when users can access specific systems based on the time of day or week. They do not appear at the end of an ACL.
C: Implicit allow does not appear at the end of an ACL.
D: An SNMP string is similar to a user id or password that permits access to a router’s or other device’s statistics. They do not appear at the end of an ACL.

Stewart, James Michael, CompTIA Security+ Review Guide, Sybex, Indianapolis, 2014, pp 26, 280.
http://en.wikipedia.org/wiki/Simple_Network_Management_Protocol