81. Which of the following worldwide interoperability for microwave access (WiMAX) operating topologies uses only the non-line-of-sight (NLOS) signal propagation?
a. Point-to-point
b. Point-to-multipoint
c. Multihop relay
d. Mobile
81. d. A mobile topology is similar to a cellular network because multiple base stations (BSs) collaborate to provide seamless communications over a distributed network to both subscriber stations (SSs) and mobile subscribers (MSs). A non-line-of-sight (NLOS) signal propagation is electromagnetic signaling that uses advanced modulation techniques to compensate for signal obstacles and enables indirect communications between transmitting stations. Mobile WiMAX topology operates on NLOS signal propagation, whereas the other three topologies use either LOS or NLOS signal propagation. A line-of-sight (LOS) signal propagation is electromagnetic signaling that is highly sensitive to radio frequency obstacles requiring an unobstructed view between transmitting stations. The other three choices are also examples of WiMAX operating topologies.
A point-to-point topology consists of a dedicated long-range, high-capacity wireless link between two sites. This topology is used for high-bandwidth wireless backhaul services at maximum operating ranges using either LOS or NLOS signal propagation. It uses a backhaul as a high-capacity line from a remote site or network to a central site or network.
A point-to-multipoint topology is composed of a central BS supporting multiple SSs, providing network access from one location to many locations. It is commonly used for last-mile broadband access, private enterprise connectivity to remote offices, and long-range wireless backhaul services for multiple sites. Last-mile broadband access refers to communications technology that bridges the transmission distance between the broadband service provider and the customer premises equipment.
A multihop relay topology, also referred to as mesh networking, is used to extend a BS’s coverage area by permitting SSs or MSs to replay traffic by acting as a relay station.
82. Which of the following worldwide interoperability for microwave access (WiMAX) operating topologies uses a concept of security zone?
a. Point-to-point
b. Point-to-multipoint
c. Multihop relay
d. Mobile
82. c. A multihop relay topology, also referred to as mesh networking, is used to extend a base station’s (BS) coverage area by permitting subscriber stations (SSs) or mobile subscribers (MSs) to replay traffic by acting as a relay station. A multihop uses a security zone concept where it is a set of trusted relationships between a BS and a group of relay stations (RSs). An RS can forward traffic to only RSs or SSs within its security zone. The other three choices, which are also examples of WiMAX operating topologies, do not use the concept of security zone.
A point-to-point topology consists of a dedicated long-range, high-capacity wireless link between two sites. This topology is used for high-bandwidth wireless backhaul services at maximum operating ranges using either line-of-sight (LOS) or no-line-of-sight (NLOS) signal propagation. It uses a backhaul as a high-capacity line from a remote site or network to a central site or network.
A point-to-multipoint topology is composed of a central BS supporting multiple SSs, providing network access from one location to many locations. It is commonly used for last-mile broadband access, private enterprise connectivity to remote offices, and long-range wireless backhaul services for multiple sites. Last-mile broadband access refers to communications technology that bridges the transmission distance between the broadband service provider and the customer premises equipment.
A mobile topology is similar to a cellular network because multiple BSs collaborate to provide seamless communications over a distributed network to both SSs and MSs.
83. Which of the following is a detective control in a local-area network (LAN) environment?
a. File backup
b. Contingency plan
c. Electronic surveillance
d. Locks and keys
83. c. Electronic surveillance is an example of detective controls. File backup is incorrect because it is an example of recovery controls. A contingency plan is incorrect because it is an example of recovery controls. Locks and keys are incorrect because they are examples of preventive controls.
84. Which of the following establishes accountability in a local-area network environment?
a. Network monitoring tools
b. Access logs
c. Lock and key systems
d. Card key systems
84. b. Access logs along with user IDs and passwords provide a reasonable amount of accountability in a local-area network (LAN) environment because user actions are recorded.
Network monitoring tools are an example of a detective control used by network management. As such they do not show any accountability of the user. They watch the network traffic and develop trends.
Lock and key systems and card key systems are examples of preventive controls as a part of physical security. Keys can be lost or stolen, and, therefore, accountability is difficult to prove and control.
85. Attackers use which of the following to distribute their warez files?
a. File transfer protocol server
b. SOCKS server
c. Web proxy server
d. E-mail server
85. a. A warez server is a file server used to distribute illegal content such as copies of copyrighted songs, movies, and pirated software. Attackers often exploit vulnerabilities in file transfer protocol (FTP) servers to gain unauthorized access so that they can use the server to distribute their warez files.
The socket security (SOCKS) server is a networking-proxy protocol that enables full access across the SOCKS server from one host to another without requiring direct IP reachability. Web proxy servers are used to access external websites. E-mail servers can be used to do proper things such as sending normal messages and sending malicious code.
86. Which of the following networks provides for movement of employees within an organization without the associated cabling costs?
a. Traditional local-area networks (LANs)
b. Metropolitan-area networks (MANs)
c. Virtual local-area networks (VLANs)
d. Value-added networks (VANs)
86. c. Virtual LANs are a logical collection of individual LANs, because they link local- and wide-area networks using routers, switches, and backbone equipment and related software so that users at various locations have access to data residing on multiple systems and locations that they would not have otherwise. The virtual network is transparent to users. Virtual LANs reassign users without changing cables when users move from one location to another. Network maintenance costs are lower and equipment moves are done faster. Another benefit of virtual LANs is that all servers in a building can be physically protected in a data center instead of spreading them throughout the building in the user departments.