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.

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.

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.

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.

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.

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.

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：Socket

UDP (User Datagram Protocol) and TCP (Transmission Control Protocol) are transport protocols used by applications to retrieve data over a network. Both use ports to communicate with the upper OSI layer and keep track of the various conversations that occur simultaneously. Ports are also the mechanism used to identify how other computers access services. When a TCP or UDP message is formed, the source and destination ports are included in the header information along with the source and destination IP addresses. This IP address and port number is called a socket; the IP address serves as the gateway to the computer and the port serves as the gateway to the actual protocol or service.

×：IP address

This is incorrect because the IP address does not tell the packet how to communicate with the service or protocol. The purpose of an IP address is to identify and address the location of a host or network interface. Each node in a network has a unique IP address. This information, along with the source and destination ports, make up a socket. The IP address tells the packet where to go, and the port indicates how to communicate with the appropriate service or protocol.

×：Port

The port is incorrect because it tells the packet only how to communicate with the appropriate service or protocol. It does not tell the packet where it should go. The IP address provides this information. Ports are communication endpoints used by IP protocols such as TCP and UDP. Ports are identified by a number.

×：Frame

Frame is incorrect because the term is used to refer to a datagram after the header and trailer have been given to the data link layer.

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.

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.

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：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.

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：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.

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.

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.

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

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：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.

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