Users report that they are unable to access network printing services. The security technician checks the router access list and sees that web, email, and secure
shell are allowed. Which of the following is blocking network printing?

A.
Port security

B.
Flood guards

C.
Loop protection

D.
Implicit deny

Explanation:
Implicit deny says that if you aren’t explicitly granted access or privileges for a resource, you’re denied access by default. The scenario does not state that network
printing is allowed in the router access list, therefore, it must be denied by default.
Incorrect Answers:
A: Port security in IT can mean the physical control of all connection points, the management of TCP and User Datagram Protocol (UDP) ports, or Port knocking.
The issue in this case, however, is that network printing is not explicitly allowed in the ACL.
B: A flood guard protects a private network against flooding or massive-traffic DoS attacks. The issue in this case, however, is that network printing is not explicitly
allowed in the ACL.
C: Loop protection is the resolving of a transmission pathway that repeats itself. It includes the use of Spanning Tree Protocol (STP) for Ethernet and the IP header
TTL value. The issue in this case, however, is that network printing is not explicitly allowed in the ACL.

Stewart, James Michael, CompTIA Security+ Review Guide, Sybex, Indianapolis, 2014, pp 24, 25, 284.