cisco ccna new exam code

cisco ccna new exam code.The above "action" of a network node is called performing routing of information, and the protocol used by each network node (also called a router) to determine the nearest next-stop node to the destination host is called a routing protocol. The unit of a message delivered at the Internet layer is called a packet.Transport layer: When a message is delivered, the sending host knows when the message is sent, but has no way of knowing whether the message will actually reach the destination host. The transport layer abstracts the next layer in order to ensure the smooth transfer of information between the two endpoints, involving the end-to-end transfer process. For example, the transport layer can detect any parts of the message that are lost during transmission. The transport layer can also provide the type of information being transmitted. As an example, a host opens an FTP transaction while requesting a web page to be opened. How should these two operations be distinguished? With the concept of transport layer ports, a host can separate these two operations at the transport layer. Different services can be enabled on different transport layer ports, for example, Web services on port 80 and FTP services on port 21. Thus, when the destination host receives a request to access port 80, it knows that it needs to pass the request to the application layer that handles Web transactions. This service provided by the transport layer is called multiplexing. The unit of a message passed at the transport layer is called a segment oThe application layer: The application layer is the highest layer of the TCP/IP protocol stack and is the layer that end users are more familiar with. Operations such as sending e-mail with a mail client or browsing a Web site with a Web browser occur at the application layer. Both of these operations correspond to specific applications, which use some sort of protocol to perform the service. Continuing from the previous example, Simple Mail Transfer Protocol (SMTP) is used to deliver email, while a browser opens a page using Hypertext Transfer Protocol (HTTP). At this layer, the protocol is not concerned with how the message is delivered to the destination host, only with defining the content of the message being delivered.Table 1-2 shows the protocols that operate at each layer of the TCP/IP model.-... Table 1-2 Protocols Operating at Each Layer of the TCP/IP ModelTCP/IP Model Layer Name Protocol NameLink layer Ethernet protocol, point-to-point (PPP) protocolInternet layer IPTransport layer TCP/UDPApplication layer HTTP, SMTP, FTP