D1

TCP/IP protocols map to a four layer conceptual model.The four layers of the model are: Application, Transport, Internet and Network Interface.Each layer in the model corresponds to one or more layers of the seven layer Open Systems Interconnection (OSI) model; (application layer, presentation layer, session layer, transport layer, network layer, data-link layer and physical layer).

Internet Layer- The Internet layers are responsible for addressing, packaging and routing functions. The core protocols of the Internet layer are IP, ARP, ICMP and IGMP.

HTTP (Hypertext Transfer Protocol)

 This protocol is used by the Web. It expresses how messages are formatted and transmitted. It allows the Web server and browsers to response to various commands. For example, when you enter a URL into browser, it actually sends an HTTP command to the Web server directing you to Web page

The Address Resolution Protocol (ARP) - This is the resolution of the internet layer address to the network interface layer address such as a hardware address.

Transport Layer - The Transport layer is responsible for providing the Application layer with session and datagram communication services. The core protocols of the Transport layer are Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

The Internet Control Message Protocol (ICMP) - This provides problem solves and reporting errors due to the unsuccessful delivery of IP packets.

The Internet Group Management Protocol (IGMP) - This is for the management of IP multicast groups.

UDP provides many connectionless and unreliable communications service. UDP is used when only small amounts of data are transferred. When the overhead of establishing a TCP connection is not wanted or when the upper layer protocols provide good delivery.

Application Layer- This gives applications the ability to access other layers and defines the protocols that applications use to exchange data. There are many application layer protocols and new protocols are always being created. The most popular application layer protocols are those used for exchanging user information. These are HTTP, FTP and SMPT.

SMTP(Simple Mail Transfer Protocol)

This is a protocol for sending e-mails between servers. E-mail systems that send mail over the Internet use SMTP, to send messages from one server to another the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is used to send messages from a mail client to a mail server. This is why you need to specify both the POP or IMAP server and the SMTP server when you configure your e-mail application.

The File Transfer Protocol (FTP)

This is used to the interactive file transfer.

The Simple Mail Transfer Protocol (SMPT)

This is used for the transfer of mail messages and attachments