〇：Make the mail relay server available to everyone.

This is a question of choosing the “ineffective” one. An open mail relay server is not an effective countermeasure against spam. In fact, spammers often use spammers to distribute spam, because the attackers can hide their identities. An open mail relay server is an SMTP server configured to allow inbound SMTP connections from anyone on the Internet, and many relays are properly configured to prevent attackers from distributing spam and pornography. Thus, the correct answer is “have an email relay server available to everyone.” will be.

×：Build a properly configured mail relay server.

A properly configured mail relay server can also suppress spam mail.

×：Perform filtering at the e-mail gateway.

Filtering emails that are considered spam mail at the gateway will help to prevent spam mail.

×：Filtering at the client.

Filtering spam mail at the client, i.e., in a mailing application such as Outlook, is considered to be a countermeasure against spam mail.

〇：Stateful Inspection

Stateful Inspection detects abnormal communication in which the request and response are linked and only the response is returned from a different server. Therefore, the correct answer is “Stateful Inspection.

×：Application Gateway

Commonly referred to as WAF, this is used when filtering is performed based on strings in telegrams, such as SQL injection.

×：Packet Filtering

Used for filtering by IP address or port.

×：Session Gateway

There is no such firewall category.

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

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.

Carrier Sense Multiple Access Collision Detection (CSMA / CD) is used for systems that can transmit and receive simultaneously, such as Ethernet. If two clients listen at the same time and make sure the line is clear, both may transmit at the same time, causing a collision. Collision Detection (CD) is added to solve this scenario. The client checks to see if the line is idle and transmits if it is idle. If in use, they wait for a random time (milliseconds). During transmission, they monitor the network and if more input is received than transmitted, another client is also transmitting and sends a jam signal instructing other nodes to stop transmitting, wait a random time and then start transmitting again.

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：IGRP

The Internal Gateway Routing Protocol (IGRP) is a distance vector routing protocol developed by and proprietary to Cisco Systems, Inc. Whereas the Routing Information Protocol (RIP) uses one criterion to find the optimal path between source and destination, IGRP uses five criteria to make an “optimal route” determination. The network administrator can set weights on these different metrics so that the protocol works optimally in its particular environment.

×：RIP  

Routing Information Protocol (RIP) is incorrect because it is not proprietary; RIP allows routers to exchange routing table data and calculate the shortest distance between source and destination. It is considered a legacy protocol due to poor performance and lack of features. It should be used in smaller networks.

×：BGP

Border Gateway Protocol (BGP) is incorrect because it is an Exterior Gateway Protocol (EGP); BGP allows routers in different ASes to share routing information to ensure effective and efficient routing between different networks. BGP is used by Internet Service Providers.

×：OSPF  

OSPF is incorrect because it is not proprietary; it uses a link-state algorithm to transmit information in the OSPF routing table. Smaller and more frequent routing table updates.

A well-known port is a port number from 0 to 1023 that is reserved for standard services. There are three port number combinations. Well-known port numbers (0-1023) are port numbers officially registered with IANA. Registered port numbers (1024-49151) are port numbers that are officially registered with IANA. A dynamic/private port number (49152-65535) is a port number that is not officially registered with IANA.

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.

〇：DNSSEC

DNSSEC is a set of extensions to the DNS that provide DNS clients (resolvers) with authentication of the origin of DNS data to reduce the threat of DNS poisoning, spoofing, and similar attack types. It is an Internet Engineering Task Force (IETF) specification for securing services.

×：Resource Record

DNS servers contain records that map hostnames to IP addresses, called resource records. The answer is incorrect. When a user’s computer needs to resolve a hostname to an IP address, it looks in its network configuration to find its DNS server. The computer then sends a request containing the hostname to the DNS server for resolution; the DNS server looks at its resource records, finds a record with this particular hostname, retrieves the address, and responds to the computer with the corresponding IP address.

×：Zone Transfer

Primary and secondary DNS servers synchronize their information via zone transfers. The answer is incorrect. After changes are made to the primary DNS server, these changes must be replicated to the secondary DNS server. It is important to configure the DNS servers so that zone transfers can take place between specific servers.

×：Resource Transfer

Equivalent to transferring DNS resource records, but the answer is incorrect.

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.

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.

The data link layer or Layer 2 of the OSI model adds a header and trailer to the packet to prepare the packet in binary format in local area network or wide area network technology for proper line transmission. Layer 2 is divided into two functional sublayers. The upper sublayer is logical link control (LLC), which is defined in the IEEE 802.2 specification. It communicates with the network layer above the data link layer. Below the LLC is the Media Access Control (MAC) sublayer, which specifies interfaces with the protocol requirements of the physical layer.

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.

〇：For early detection or enclosure in the event of an attack.

Attackers will conduct an investigation before launching a substantial attack. In such cases, a vulnerable network can provide preventative information such as where the attacker is accessing the network from. This is because only an attacker would have the incentive to break into the network. Vulnerable network domains, such as honeypots, make this kind of intrusion easier and clarify the attacker’s behavior. Thus, the correct answer is “to detect or enclose them early in the event of an attack.” will be

×：Debugging environment for when a system outage occurs in the current environment.

The answer is not to intentionally create a vulnerable environment. It is only the result of creating an environment that is vulnerable.

×：Aiming to prevent regressions due to old vulnerabilities.

Even if it is an old vulnerability, it should be addressed and there is no point in allowing it to remain.

×：A special environment for running a product with a low version that is no longer supported.

It is not an answer to intentionally create a vulnerable environment. It is merely the result of creating an environment that is vulnerable.

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.

〇：3-tier architecture

The 3-tier architecture clearly distinguishes the three layers: the client has the user interface responsible for input and displaying results, and the server has the functional process logic responsible for data processing and data storage for accessing the database. The user interface role is generally handled by the front-end web server with which the user interacts. It can handle both static and cached dynamic content. The functional process logic is where requests are reformatted and processed. It is typically a dynamic content processing and generation level application server. Data storage is where sensitive data is held. It is the back-end database and holds both the data and the database management system software used to manage and provide access to the data.

×：2-tier architecture

Two-tier, or client/server, is incorrect because it describes an architecture in which a server serves one or more clients that request those services.

×：Screened Subnets

A screen-subnet architecture is for one firewall to protect one server (basically a one-tier architecture). The external, public-side firewall monitors requests from untrusted networks like the Internet. If one layer, the only firewall, is compromised, an attacker can access sensitive data residing on the server with relative ease.

×：Public and Private DNS Zones

Separating DNS servers into public and private servers provides protection, but this is not the actual architecture.

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：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.