ccna sybex 8th edition pdf

ccna sybex 8th edition pdf.. Well-known ports: Port numbers 0 ~ 1023, assigned by the Internet Address Assignment Authority (IANA) to applications commonly used on the Internet, such as HTTP, DNS, and SMTPo. Registered ports: port numbers 1024 ~ 49151, assigned by IANA to dedicated applications such as Microsoft SQLServer, Shockwave, Oracle, etc.. Dynamically assigned port: Port number 49152.65535, dynamically assigned by the operating system for use by a session.When connecting to an application on the target host, the source port field of the TCP or UDP header will contain a dynamically assigned port, and the target port field will contain either the famous port or the registered port - depending on the connected application. The destination host can determine which application to give the session data to for processing based on the destination port.For a complete list of ports and names, see www.iana.org/assignments/port-numbers. Note that some applications support TCP, some support UDP, and some (such as DNS) support both. DNS uses UDP for querying and resolving, but uses TCP OBe sure to remember the following applications and ports that use TCP: HTTP (80), FTP (21), P0P3 (110), SMTP (25), SSH (22), and Telnet (23); be sure to remember the following applications and ports that use UDP: DNS queries (53), RIP (520), SNMP (161), and TFTP (69). ( 69).8.3.2 Application MappingTCP and UDP provide multiplexing capabilities to support multiple sessions to one or more hosts simultaneously, which allows multiple applications to send and receive data simultaneously. When using these protocols, sessions are distinguished based on port number (transport layer) and IP.(Internet layer).However, as in Tables 8.1 and 8.2, the data segment contains two port numbers: the source port number and the destination port number. When you initiate the establishment of a connection to a remote application, the operating system will pick a currently unused port number from 49152-65535 and use it as the source port number in the TCP or UDP header; the application will populate the destination port number field with its well-known or registered port number. Upon receipt of the data segment, the target device determines which application should be given the data segment for processing based on the destination port number. The same is true for traffic returning from the target device.Take a look at an example of session multiplexing using TCP, as shown in Figure 8.1. In this example, there are two Telnet connections between PC.A and the server. These connections are known to be Telnet connections based on the target port number (23); the target device knows that the Telnet process should be started when it receives a connection establishment request. Also, notice that the source port numbers of the two connections are different, 50000 and 50001, which allows the PC and the server to distinguish between their Telnet sessions. This is a simple example of connection multiplexing.