VoIP uses UDP. It is real-time oriented, and it is probably better to lose one or two packets than to retransmit a few seconds later in a connectionless fashion.

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.

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：How routers are centrally managed and control packets based on the controller’s instructions 

Software-defined networks (SDN) are intended to facilitate centralized management of routing decisions and to separate the router’s logical functions of passing data between the routing decision and the interface and making its mechanical functions.SDN architecture is a scalable, a programmable, and is intended to be a standard method of providing router control logic. Therefore, the correct answer is “a way for routers to be centrally managed and control packets based on the controller’s instructions.

×：Mapping between MAC and IP addresses.

ARP table.

×：Updating the routing table in a dynamic way.

Explanation of dynamic routing.

×：A method in which routers communicate with each other to update the routing table when an event occurs.

This is an explanation of routing control in case of communication failure.

〇：SMTP lacks proper authentication mechanisms.

Email spoofing is easy to perform if the SMTP lacks proper authentication mechanisms. An attacker can spoof the sender address of an e-mail by sending a Telnet command to port 25 of the mail server. The spammer uses e-mail spoofing to prevent himself from being identified.

×：The administrator forgot to configure a setting that prevents inbound SMTP connections for non-functioning domains.

If it is spoofed, the email sender is also spoofed. This can happen even if you prevent inbound SMTP connections for a domain.

×：Technically abolished by keyword filtering.

Filtering is not very effective against spoofing. Therefore, even if it is technically obsolete, it is unlikely to be the cause.

×：The blacklist function is not technically reliable.

If an email is spoofed, the sender of the email is also spoofed. This can happen even if the filtering function is not reliable.

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.

Point-to-Point Tunneling Protocol (PPTP) is a way to implement a virtual private network (VPN). It is Microsoft’s proprietary VPN protocol that operates at the data link layer of the OSI model; PPTP can only provide a single connection and can operate over a PPP connection.

〇：TLS is an open community version of SSL.

Secure Sockets Layer (SSL) and Transport Layer Security (TLS) are cryptographic protocols used to protect communications by encrypting segments of a network connection. SSL is a proprietary protocol and TLS was developed by a standards body, making it an open community protocol.

×：TLS is an open community version of SSL. SSL is a proprietary protocol and TLS was developed by a standards body, making it an open community protocol. x: The SSL protocol can be modified by developers to extend its capabilities.

This is incorrect because SSL is a proprietary protocol developed by Netscape. This means that the technical community cannot easily interoperate and extend SSL to extend to its functionality.

×：SSL is an open community protocol while TLS is a proprietary protocol.

The meaning and matching are reversed.

×：SSL is an extended version and backward compatible with TLS.

Wrong, since TLS is actually more extensible than SSL and is not backward compatible with SSL.

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.

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.

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：Unified Threat Management

Unified Threat Management (UTM) appliance products have been developed to provide firewall, malware, spam, IDS / IPS, content filtering, data leak prevention, VPN capabilities, and continuous monitoring and reporting in computer networks.

Since this question asks for a definition of Unified Threat Management that is unfamiliar or not even mentioned in the course material, it is inefficient to buy and study a new book just to get this score. To avoid ending up with “I don’t know = I can’t solve it,” be sure to develop the habit of choosing a “better answer.

If you think in terms of the classification Concepts/Standards > Solutions/Implementation Methods, ISCM (NIST SP800-137) and centralized access control systems are the former, while Unified Threat Management and cloud-based security solutions are the latter. Therefore, it is still better to bet on unified threat management and cloud-based security solutions.

×：ISCM (NIST SP800-137)

Because continuous monitoring in the security industry is most commonly Information Security Continuous Monitoring ISCM (NIST SP800-137), which enables companies to gain situational awareness, continuous awareness of information security, vulnerabilities, and threats to support business risk management decisions , is incorrect.

×：Centralized Access Control System

Wrong because a centralized access control system does not attempt to combine all of the security products and capabilities mentioned in the issue. A centralized access control system is used so that its access control can be enforced in a standardized manner across different systems in a network environment.

×：Cloud-based security solutions

Cloud-based security solutions include security managed services that allow an outsourced company to manage and maintain a company’s security devices and solutions, but this is not considered a cloud-based solution. The cloud-based solution provides the infrastructure environment, platform, or application to the customer so that the customer does not have to spend time and money maintaining these items themselves.

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.

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.

Sender Policy Framework (SPF) is an email verification system that detects email spoofing and prevents spam and malicious email. Attackers typically spoof e-mail addresses to make recipients believe that the messages come from a known and trusted source. SPF allows network administrators to specify which hosts can send mail from a particular domain by implementing SPF records in the Domain Name System (DNS). The e-mail server is configured to check with the DNS server to ensure that e-mail sent from a particular domain was sent from an IP address authorized by the administrator of the sending domain.

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.

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：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.

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.

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.