ccna to aws

ccna to aws.The last part of the handshake is the ACK, which is transmitted in the same way as described in the section "PC.A sends TCPSYN to PC-B", except that the ACK flag is set instead of the SYN flag. Again, there is no need to perform ARP, and the switch does not need to perform any learning process, as this was done when PC-A sent SYN to PC-B.When the Telnet process is complete, the user enters exit to end the Telnet session, which will close the session properly; PC-A will send a TCP data segment with the FIN flag set; upon receipt of this end message, PC-B will respond with a TCP data segment with the FIN and ACK (FIN/ACK) flags set, indicating that the Telnet session has ended. The flag (code bit) RST is used to indicate that the session is about to terminate abnormally.End-to-End Transfer ExampleIf you do not understand what is discussed in this section, refer to Chapters 2, 3, 4, 5, 6, and 8, which discuss the subject in more detail. This chapter is included in this book for two reasons: First, you may encounter some exam questions about PDUs and how they are created as data is transmitted over the network, so you must review this section and the information in Table 9.1, Table 9.2, and Table 9.3 well. Be sure to know what kind of MAC address the Ethernet header contains and the port number used for TCP; also know how PDUs are created in the direction from the source device to the destination device and from the destination device to the source device.Second, this chapter combines the knowledge presented in the previous chapters from a practical perspective, which can help you troubleshoot problems. You may encounter troubleshooting-related questions, such as "What message will you see if the intermediate router does not know how to get to the destination?" , "How do you determine if there is a problem with the NIC?" , "How can you be sure that the TCP/IP stack of the host is working properly? "It is important to know how ICMP works and the various ICMP messages you might see. See Chapter 5 for more information on this.9.3 Authentication SummaryThis chapter focuses on how to use TCP/IP to transport PDUs over an Ethernet-based network o First, it briefly reviews the devices running at the physical, data link, and network layers (hubs, NICs, and switches, routers), as well as MAC addressing and TCP/IP addressing; then, it details how devices obtain IP addressing information via DHCP, how to use DNS to resolve names to IP addresses, and how to use Then, it details how the device obtains IP addressing information via DHCP, how to resolve names to IP addresses using DNS, and how to set up and tear down Telnet sessions using TCP. All of this knowledge is covered in Chapters 2, 3, 4, 5, 6, and 8, but using it in conjunction with an exhaustive example helps you gain a comprehensive understanding of how network devices interact with each other and how PDUs are created on each segment through which data is transmitted.94 Two-Minute Sprints -Reviewing Network Devices and Addressing. Hubs forward letters at the physical layer Switches and NICs handle Ethernet frames and MAC addresses at the data link layer, while routers handle packets and IP addressing at the network/Internet layer.