CISCO Cyberops Security Fundamentals Section 01: TCP/IP Protocol Suite (Q 31-40)

UDP operates at Layer 4 of the OSI model, which is the Transport layer. This layer is responsible for establishing connections and ensuring reliable delivery of data between end systems. UDP (User Datagram Protocol) is a connectionless protocol that provides a low overhead and fast transmission of data, but does not guarantee delivery or order of packets. It is commonly used for applications that require real-time communication, such as streaming media or online gaming.

The correct answer is 1. SYN; 2. SYN, ACK; 3. ACK. The three steps in the TCP 3-way handshake are as follows: 1) The client sends a SYN (synchronize) packet to the server to initiate a connection request. 2) The server responds with a SYN-ACK (synchronize-acknowledge) packet, indicating that it received the client's request and is willing to establish a connection. 3) The client acknowledges the server's response by sending an ACK (acknowledge) packet, confirming the establishment of the connection. This completes the 3-way handshake and both parties can now start exchanging data.

The window field in a TCP header identifies the number of octets that the device is willing to accept. This field is used for flow control, allowing the receiving device to inform the sender about the amount of data it can receive and process at a given time. By adjusting the window size, the sender can optimize the transmission rate and prevent overwhelming the receiver.

Both the sender and receiver generate sequence numbers during TCP connection establishment. This is because TCP uses a mechanism called the "three-way handshake" to establish a connection. In this process, the sender sends a SYN packet with a sequence number, and the receiver responds with a SYN-ACK packet containing its own sequence number. Finally, the sender acknowledges the receipt of the SYN-ACK packet by sending an ACK packet with another sequence number. Therefore, both the sender and receiver generate sequence numbers to ensure reliable communication and synchronization between the two ends of the connection.

The correct answer is "checksum". The UDP header includes a checksum field, which is used to ensure the integrity of the data being transmitted. The checksum value is calculated by the sender and then verified by the receiver to detect any errors or corruption in the data. This helps to ensure that the data is delivered accurately and without any errors.

UDP is a transport layer protocol that operates at Layer 4 of the OSI model. It uses IP protocol number 17 to identify itself. Unlike TCP, UDP is connectionless and does not establish a reliable connection between the sender and receiver. Therefore, it does not guarantee data delivery.

Telnet, SSH, and FTP are all TCP applications because they utilize the Transmission Control Protocol (TCP) as the underlying transport protocol for communication. Telnet is a protocol that allows remote terminal access to a computer, SSH is a secure network protocol used for secure remote login and file transfer, and FTP is a standard network protocol used to transfer files between a client and a server over a TCP-based network. Therefore, these three options are TCP applications.

TFTP (Trivial File Transfer Protocol) and SNMP (Simple Network Management Protocol) are both examples of UDP (User Datagram Protocol) applications. UDP is a connectionless protocol that provides fast and lightweight communication, making it suitable for applications that require low latency and minimal overhead. TFTP is a simple file transfer protocol commonly used for transferring small files, while SNMP is used for managing and monitoring network devices. SMTP (Simple Mail Transfer Protocol) and FTP (File Transfer Protocol) are both examples of TCP (Transmission Control Protocol) applications, which provide reliable and ordered data delivery.

When a client connects to a server that is listening on a well-known port, it dynamically uses an ephemeral port as its source port. Ephemeral ports are temporary ports that are randomly assigned by the client's operating system from a range of available ports. These ports are used for the duration of the connection and are typically higher in number to avoid conflicts with well-known ports. Using ephemeral ports allows multiple client-server connections to coexist on the same client system.

A TCP segment is a unit of data sent over a TCP connection. The source port is a field in the TCP segment that identifies the sending application or process. The window size field specifies the number of bytes that can be sent before requiring an acknowledgment. The checksum field is used for error detection in the TCP segment. Therefore, the correct answer is source port, window size, and checksum.