〇：Softphones are safer than IP phones. 

IP softphones should be used with caution. A softphone is a software application that allows users to make calls via computer over the Internet. Replacing dedicated hardware, a softphone works like a traditional telephone. Skype is an example of a softphone application. Compared to hardware-based IP phones, softphones are more receptive to IP networks. However, softphones are no worse than other interactive Internet applications because they do not separate voice traffic from data, as IP phones do, and also because data-centric malware can more easily enter the network through softphones. network.

×：VoIP networks should be protected with the same security controls used on data networks.

The statement is incorrect because it correctly describes the security of an IP telephony network. an IP telephony network uses the same technology as a traditional IP network, which allows it to support voice applications. Therefore, IP telephony networks are susceptible to the same vulnerabilities as traditional IP networks and should be protected accordingly. This means that IP telephony networks should be designed to have adequate security.

×：As an endpoint, IP telephony can be a target of attack.

Incorrect because true: An IP phone on an IP telephony network is equivalent to a workstation on a data network in terms of vulnerability to attack. Thus, IP phones should be protected with many of the same security controls implemented on traditional workstations. For example, the default administrator password must be changed. Unnecessary remote access functions need to be disabled. Logging should be enabled and the firmware upgrade process should be secured.

×：The current Internet architecture in which voice is transmitted is more secure than physical phone lines.

True and therefore incorrect. In most cases, the current Internet architecture in which voice is transmitted is more secure than physical telephone lines. Physical phone lines provide a point-to-point connection, which is difficult to leverage over the software-based tunnels that make up the bulk of the Internet. This is an important factor to consider when protecting IP telephony networks because the network is now transmitting 2 valuable asset data and voice. It is not unusual for personal information, financial information, and other sensitive data to be spoken over the phone; intercepting this information over an IP telephony network is as easy as intercepting regular data. Currently voice traffic should also be encrypted.

Application firewalls target Layer 7 of the OSI. The main advantage of an application firewall is its ability to understand specific applications and protocols. Packets are not decrypted until Layer 6, so Layer 7 can see the entire packet. Other firewalls can only inspect the packet, not the payload. It can detect if an unwanted application or service is trying to bypass the firewall by using a protocol on an allowed port, or if the protocol is being used in a malicious manner.

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.

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

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.

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.

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.

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：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.

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.

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.

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：LAND attack

A LAND attack is an attack that penetrates firewalls that block bad requests; it is similar to the Fraggle attack, but it sends a request to the firewall with the sender as the target of the attack. This is a blind spot because the firewall, which is supposed to protect the inside of the system, is used for the attack.

×：Teardrop

Teardrop is an attack that halts the system by forging the offset of IP packets before they are split.

×：Christmas Tree Attack

A Christmas tree attack is an attack in which a packet is sent with a number of flags (URG, ACK, PSH, RST, SYN, FIN) and the response is observed.

×：CHARGEN attack

CHARGEN (port 19) is a protocol that returns an appropriate string.

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.

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：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.

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.

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.