cisco certification 200-120

cisco certification 200-120.Similarly, for that HTTP connection (Web service), the socket of host A is (10.0.1.1, 1027) and the socket of host B is (10.0.2.2, 80), where 80 is the standard port number assigned to the HTTP service. The previous examples illustrate the concept of multiplexing and sockets as it applies to TCP connections, and the same concept applies to UDP. Let's say that when a DNS resolver initiates a DNS query to a DNS server, as described in Section 1.6, ...... UDP sockets are also established between the DNS resolver and the DNS server. There is also a concept that usually involves whether a connection needs to be formally established at the transport layer before data can be transmitted between devices. According to this concept, protocols can be divided into the following two types.Connection-oriented protocols: a connection needs to be formally established before data can be transmitted over a connection-oriented protocol. TCP is a connection-oriented protocol and establishes a connection by 3 packets before transmitting data. Connection-oriented protocols generally have a mechanism to terminate the connection. Connection-oriented protocols are more reliable because connection establishment allows exchange of settings and ensures that the receiver can receive the packet. The disadvantage of such protocols is the increased overhead and delay in the transmission of information. Connectionless protocols: no connection needs to be established before data can be transmitted over a connectionless protocol. UDP belongs to theon connectionless protocols. This is a closer look at how TCP and UDP work.1.8.1 Transmission Control Protocol (TCP)The Transmission Control Protocol (TCP) is a reliable, connection-oriented protocol for Internet communication. Connection-oriented means that before any data can be transmitted over TCP, two hosts need to exchange some special packets with each other to establish TCP1.8 Transport Layer Technologies and Protocols 97connection. Connectionless protocols (e.g., UDP), on the other hand, do not require any connection to be established before data can be transmitted. As described in RFC 793, which defines the TCP protocol, TCP "self-identifies" that the datagrams (IP packets) it obtains from the underlying protocol are simple, and perhaps unreliable. TCP provides most of the services one would expect a transport layer protocol to provide. This section describes the following services provided by TCP and the following features it has. Multiplexing.Connection establishment and termination.Reliability (error detection and recovery).