IP addresses and port numbers together make this possible. There can be more than one connection between two hosts at the same instance. The sole purpose of this layer is to create sockets over which the two hosts can communicate (you might already know about the importance of network sockets) which is essential to create an individual connection between two devices. The Simple Mail Transfer Protocol ( SMTP) The Simple Network Management Protocol ( SNMP) By the time you come back, you will be able to visualize and answer all of these questions on your own. If you have any confusion regarding the basics of networking protocols, I would recommend that you do a quick revision before proceeding ahead, as this book requires familiarity with the TCP/UDP protocols.

The TCP/IP model takes care of every aspect of every packet's life cycle, namely, how a packet is generated, how a single packet gets attached with a required set of information (PDU), how a packet is transmitted, how it comes to life, how it is routed through to intermediary nodes to the destination, how it is integrated back with other packets to get the whole information out, and so on. The TCP/IP model was originally known as the DoD model, and the project was regulated by United States Department of Defense. Even the world of computers needs a set of rules and regulations to communicate, and this is taken care by the networking protocols, which govern the transmission of packets/segments/frames over a dedicated channel between hosts. In order to understand how all these things stick together, we need to understand the basics of the TCP/IP model.

Next, it's time to discuss the most important topic in the world of networking.

In layman terms what does wireshark do