Chapter 3 summary and review
|What is the 7 steps process for converting human communication to data?|| 1) The user inputs data using hardware interface|
2) Hardware and software convert data to digital format
3) Application layers services initiate the data transfer
4) OSI layers encapsulate data down the stack
5) Data is ready to be processes by the end device
|describe the two forms of application layer software and the purpose of each.||Application software has to forms: application and services.|
Applications are designed to interact with us. the application will initiate data transfer when user clicks send. Services are background programs that perform a particular function in a data network. services are invoked by devices connectint to the network or services.
|What is the meaning of server and client in the context of data network||The source end of data communication is referred to as the "server" and the receiving end is called the client. services include: DNS. FTP, HTTP, Telnet.|
|compare and contrast client/server with peer-2-peer data transfer over network.||In client server data is hosted by server. with peer-2-peer data transfer both client and server services are used within the same conversastion. hosts are equal anyone can have the data and feed it to the other.|
|What is the purpose of the DNS, HTTP, SMB, and SMTP/POP application layer protocals||All these protocols use a client/server process.|
Domain Name System (DNS) provides users with an automated service that matches or resolves resource names and email domains with the required numeric device network address. This service is available to any user connected to the Internet and running an application layer application such as a web browser or email client program.
Hypertext Transfer Protocol (HTTP) was originally developed to publish and retrieve Hypertext Markup Language (HTML) pages and is now used for distributed, collaborative, hypermedia information systems. HTTP is used by the World Wide Web (WWW) to transfer data from web servers to web clients.
Server Message Block (SMB) describes the structure of sharing network resources, such as directories, files, printers, and serial ports between computers.
Simple Mail Transport Protocol (SMTP) transfers outbound e-mails from the e-mail client to the e-mail server and transports e-mail between e-mail servers and so enables-mail to be exchanged over the Internet.
POP, or POP3 (Post Office Protocol version 3), delivers e-mail from the e-mail server to the client.
|Compare and contrast the messages that pplication layer protocols such as DNS, HTTP, SMB and SMTP/POP exchange in order data transfer to accur||DNS includes standard queries, responses, and data formats. DNS protocol communications are carried in a single format called a message. This message format is used for all types of client queries and server responses, error messages and for the transfer of resource record information between servers.|
HTTP is a request/response protocol:
A client application layer application, typically a web browser, sends a request message to the server.
The server responds with the appropriate message.
The protocol also includes messages to upload data to the server, as when completing an online form.
SMB messages use a common format to:
start, authenticate, and terminate sessions
control file and printer access
allow an application to send or receive messages to or from another device
SMTP specifies commands and replies that relate to session initiation, mail transaction, forwarding mail, verifying mailbox names, expanding mailing lists, and the opening and closing exchanges.
POP is a typical client/server protocol with the server listening for client connections and the client initiating the connection to the server. The server can then transfer the e-mail.
All above protocols use server/client request/response messages. Whereas users see the applications that use HTTP (a web browser), SMB (file manager) and SMTP/POP (email client), DNS operation underlies these applications and is truly transparent to the user.