Chapter 3: Application Layer functionally and protocols

List the six step process for converting human communications to data.

1. The user inputs data using a hardware interface 2. The application layer prepares human communication for transmission over the data network 3. Software and hardware convert data to a Digital format 4. Application services initiate the data transfer 5. Each layer plays it role, and the OSI layers encapsulates data down the stack. Encapsulated data travels across the media to the destination. OSI layers at the destination decapsulate the data up the stack. 6. Data is ready to be processed by the end device

What is GET? a. a client request for data b. protocol that uploads resources or content to the web server c. a protocol that uploads information to the server to plain text that can e intercepted and Read d. a response from a server

A. GET is a client request for data.

The Linus and UNIX operating systems are SAMBA, which is a version of which protocol? a. SMB b. HTTP c. FTP d. SMTP

A. The Linus and UNIX operating systems provide a method of sharing resources with Microsoft networks using a version of SMB called SAMBA.

Describe the two forms of application software and the purpose of each.

Application software has two forms: application and services. - Applications are designed to interact with us. Application is software for the user. If the device is a computer, the application is typically initiated by the user. Although there can be many layers of support underneath, application software provides and interface between humans and the hardware. The application will initiate the data transfer process when the user clicks the Send button or performs a similar action. - Services are background programs that perform a particular function in the data network. Services are invoked by a device connecting to the network or by an application. For example, a network service can provide functions that transmit data or provide conversion of data n a network. In general, services are not directly accessible or seen by the end user. They provide the connection between an application and the network.

DHCP allows the automation of what?

Assignment of IP addresses, subnet masks and default gateway. The protocol automates the assignment of IP addresses, subnet masks, gateway and other IP networking parameters.

The TCP/IP application layer consists roughly of which three OSI layers? a. Applications, session, transport b. application, presentation, session c. application, transport, network d. application, network, data link

B. The functionality of the TCP/IP application layer protocols fits roughly into the framework of the top three layers of the OSI model : application, presentation and session.

FTP requires ......connection (s) between client and server to successfully transfer files a. 1 b. 2 c. 3 d. 4

B. To successfully transfer files, FTP requires to connections between the client and the server ; one for commands and replies and another for the actual file transfer.

Which of the following is a connection using Telnet? a. File transfer protocol (FTP) session b. Trivial file transfer protocol (TFTP) session c. Virtual terminal (VTY) session d. Auxiliary (AUX) session

C. A connection using Telnet is called a VTY session, or connection.

HTTP is used t do which of the following? a. resolve internet names to IP addresses b. provide remote access to servers and networking devices c. transfer files that make up the web pages of the World Wide Web d. Transfer the mail messages and attachments

C. Hypertest Transfer Protocol (HTTP) is used to transfer files that make up the web pages of the World Wide Web. DNS is used to resolve internet names to IP addresses, and Telnet is used to provide remote access to servers and networking devices.

DHCP enables clients on a network to do which of the following? a. have unlimited telephone conversation b. play back video streams c. obtain IP addresss d. Track intermittent denial of service attacks

C. The Dynamic Host Configuration Protocol (DHCP) enables clients on a network to obtain IP addresses and other information from a DHCP server.

in the client/server model, the device requesting the service is refereed to as the ...........

Client. Even though a device can serve as a client and a server at times, the device requesting a service is denied as the client as the drives providing the service is defined as the server.

Which of the most popular network service? a. HTTP b. FTP c Telnet d. email

D. Email the the most popular network service, has revolutionised how people communicate through its simplicity and speed. Choice A, is incorrect because HTTP is a protocol, not a service.

The application layer is ........... of the OSI model. a. Layer 1 b. Layer 3 c. Layer 4 d. Layer 7

D. Layer 7 is the application layer and its components: applications, services and protocols.

Post Office Protocol (POP) uses which port? a. TCP/UDP port 53 b. TCP port 80 c. TCP port 25 d. UDP port 110

D. Post Office Protocol (POP) uses UDP port 110

What does FTP stand for, and what is it used for?

FTP stands for File Transfer Protocol. IT is used to move files on the network. FTP was developed to allow file transfers between a client and a server. An FTP client is an application that runs on a computer that is used to push and pull files from a server.

HTTP is referred to as a request/repsonse protocol. What are these typical message formats?

GET, PUT and POST. GET is a request ; PUT and POST provide uploading.

Elaborate on the meaning of the terms server and client in the context of data networks.

The source end of data communication is referred to as the server, and the receiving end is called the client. The client and server processes are application layer services that provide the foundation for data network connectivity. In some cases, the servers and clients are devices that perform the role specifically and exclusively. For example: - A central file server can contain an organisation business data files that employees access using their client only workstation - Internet based examples include web servers and mail servers, where many users access a centrally provided service. - In other situations, such a as file sharing over a home network, individual devices can perform both server and client roles at different times. Servers are both repository and a source of information such as text files, data bases, pictures video or audio files that have been previously recorded. Client processes at the other end of the communication across the data network allow the user to make requests to obtain the data from a server. The client software typically uses a program initiated by a user. The client initiates communication data flow from the server by sending requests for the data to the server. The server responds by starting to send one or more streams of data to the client. in addition to the actual data transfer, this exchange can include user authentication and identification of the data file to be transferred. Examples of common client/server services include the following: - DNS (Domain Name Service) - FTP - HTTP - Telnet (Teletype Network Service)

Is eBay a peer - to - peer or client/ server application?

eBay is a client/server application, eBay is implemented as a web server that responds to web client (browser) requests using HTTP.