〇：IP Session Restriction via Media Gateway

The VoIP Media Gateway translates Internet Protocol (VoIP) voice over time division multiplexing (TDM) voice to and from. As a security measure, the number of calls through the Media Gateway should be limited. The Media Gateway is vulnerable to denial-of-service attacks, hijacking, and other types of attacks.

×：Identification of Rogue Devices  

Incorrect, as rogue devices on both IP telephony and data networks need to be identified.

×：Implementation of Authentication

Incorrect because authentication is recommended for both data and voice networks.

×：Encryption of packets containing sensitive information

Incorrect because sensitive data can be transmitted over either voice or data networks and must be encrypted in both cases. Eavesdropping is a very real threat for VoIP networks.

There are many different types of distributed denial of service (DDoS) attacks; there is no IPSec flood; UDP flood, SYN flood, and MAC flood are all distributed denial of service (DDoS) attacks.

Onion routing is characterized by multiple layers of encryption because encryption is applied each time it passes through a router. However, there is no security feature at the final router because all encryption is decrypted at the final point of the router and becomes plaintext.

〇：Security

Voice over Internet Protocol (VoIP) refers to a transmission technology that delivers voice communications over an IP network; IP telephony uses technology that is similar to TCP/IP and therefore similar in its vulnerabilities. Voice systems are vulnerable to application manipulation and unauthorized administrative access. It is also vulnerable to denial of service attacks against gateway and network resources. Eavesdropping is also a concern since data traffic is transmitted in clear text unless encrypted.

The term security is a difficult answer to choose from because it has a very broad meaning. However, information security scriptures such as CISSP are persistent in saying that VoIP has vulnerabilities. Although this answer is a bit over the top in practical terms, it was made to educate the public, because depending on the creator’s intentions, this issue may arise.

×：Cost

Wrong, because cost is an advantage of VoIP; with VoIP’s, a company becomes a dedicated alternative to a separate network dedicated to data transmission and voice transmission. For telephony features such as conference calling, call forwarding, and automatic redialing are freed up in VoIP, which is open source, while companies that use traditional communications charge for VoIP.

×：Convergence

Wrong because convergence is the advantage of VoIP. Convergence means the integration of traditional IP networks with traditional analog telephone networks.

×：Flexibility

Wrong, because flexibility is an advantage of VoIP. The technology is very simple, easy and supports multiple calls over a single Internet broadband connection.

Matrix is not a network topology. Ring, mesh, and star are network topologies.

War Dialing is the indiscriminate and repeated act of cracking dial-ups in search of dial-up lines, such as those for non-public internal networks. It automatically scans a list of telephone numbers, usually dialing all numbers in the local area code, and searches modems, computers, bulletin board systems, and fax machines.

〇：VLAN

Virtual LANs (VLANs) allow logical isolation and grouping of computers based on resource requirements, security, or business needs, despite the standard physical location of the system. Computers in the same department configured on the same VLAN network can all receive the same broadcast messages, allowing all users to access the same types of resources regardless of their physical location.

×：Open Network Architecture  

Open network architecture is wrong because it describes the technology that can configure a network; the OSI model provides a framework for developing products that operate within an open network architecture.

×：Intranet

Incorrect because an intranet is a private network used by a company when it wants to use Internet and Web-based technologies in its internal network.

×：VAN  

Incorrect because a Value Added Network (VAN) is an electronic data interchange (EDI) infrastructure developed and maintained by a service bureau.

Circuit switching is a dedicated communication channel through a network. The circuit guarantees full bandwidth. The circuit functions as if the nodes were physically connected by cables.

Each IPSec VPN device will have at least one security association (SA) for each secure connection it uses; the SA, which is critical to the IPSec architecture, is the device’s need to support IPSec connections over VPN connections This is a record of the configuration that needs to be in place.

〇：OSI reference model

The OSI reference model is a seven-layer classification of network communication. The concepts of application communication and session are separated, which would be clearly communicated based on the OSI reference model. Therefore, the correct answer is “OSI reference model.

×：TCP/IP model

The TCP/IP model is a layer design that is closer to the concept of a system than the OSI reference model; in the TCP/IP model, the application layer, presentation layer, and session layer of the OSI reference model are represented by a single application layer.

×：Data link model

There is no such model.

×：Biba model

Biba model is one of the security models that indicates that data cannot be changed without permission.

〇：DNS Hijacking

The DNS plays a great role in the transmission of traffic on the Internet; it directs traffic to the appropriate IP address corresponding to a given domain name DNS queries can be classified as either recursive or iterative. In a recursive query, the DNS server forwards the query to another server, which returns the appropriate response to the inquirer. In an iterative query, the DNS server responds with the address of another DNS server that may be able to answer the question and then proceeds to further ask for a new DNS server. Attackers use recursive queries to pollute the caches of DNS servers.

The attacker sends a recursive query to the victim’s DNS server asking for the IP address of the domain; the DNS server forwards the query to another DNS server. Before the other DNS server responds, the attacker inserts his IP address. The victim server receives the IP address and stores it in its cache for a specific period of time. The next time the system queries the server for resolution, the server directs the user to the attacker’s IP address.

×：Manipulating the hosts file

Manipulating the hosts file is wrong because it does not use recursive queries to pollute the DNS server cache. The client queries the hosts file before issuing a request to the first DNS server. Some viruses add the antivirus vendor’s invalid IP address to the hosts file to prevent the virus definition file from being downloaded and to prevent detection.

×：Social engineering

Social engineering is wrong because it does not require querying DNS servers. Social engineering refers to manipulation by an individual for the purpose of gaining unauthorized access or information.

×：Domain Litigation

Domain litigation is wrong because it does not involve poisoning the DNS server cache. Domain names are at trademark risk, including temporary unavailability or permanent loss of established domain names.

Diameter is an authentication protocol that implements the AAA (Authentication, Authorization, Accounting) service, the successor to RADIUS. This can cause performance degradation and data loss. This can lead to performance degradation and data loss.

IEEE 802.11 is one of the wireless LAN standards established by IEEE.

A captive portal is a mechanism that restricts communication with the outside world until user authentication, user registration, and user consent are performed when a terminal connects to the network.

Ethernet is a way of communication used for local area networks; LANs and such communicate over Ethernet. In other words, most communication is now done over Ethernet.

Computer worms are standalone malware computer programs that replicate themselves and spread to other computers. They typically operate at OSI reference layers 5-7.

〇：Content Delivery Network (CDN)

Content delivery networks (CDNs) are designed to optimize the delivery of content to clients based on their global topology. In such a design, multiple web servers hosted at many points of existence on the Internet are globally synchronized and contain the same content, and the client is usually directed to the nearest source via DNS record manipulation based on geolocation algorithms for can be directed to.

×：Distributed Name Service (DNS)

Wrong, as there is no protocol called Distributed Name Service; DNS refers to the Domain Name Service protocol.

×：Distributed Web Service (DWS)

Distributed Web Services is also wrong because it is an incorrect answer. The concept of a distributed Web services discovery architecture is not a formal protocol, although it has been discussed by the IEEE and others.

×：Content Domain Distribution (CDD)

The term Content Domain Distribution (CDD) does not appear in CISSP’s CBK terminology.

〇：Teardrop

Teardrop is an attack to bring a system to a halt by forging the offset of IP packets when they are returned before splitting.

×：Fraggle attack

Fraggle attack is an attack that uses the CHARGEN function to generate an appropriate string.

×：CHARGEN attack

There is no attack with such a name.

×：War Driving

Wardriving is the act of driving around a city looking for vulnerable wireless LAN access points.

UDP (User Datagram Protocol) floods are often used in distributed denial of service (DDOS) attacks because they are connectionless and yet allow for easy generation of UDP messages from various scripting and compilation languages. UDP is a datagram protocol.