INTERNETWORKING I
Chapter 15 Study Guide
What layer of the OSI model is closest to the user?
the application layer
(Layer 7)
What is the definition of the Application Layer?
Determines whether sufficient resources exit for communication between systems. It does not provide services to any other Layer. It does provide a direct interface for the rest of the OSI model by using network applications or an indirect interface by using standalone applications with a redirector.
What is a redirector? What does it do?
it is a protocol. It
works with computer operating systems and network clients instead of specific
application programs. For example, if a client wants to save a file from a word
processor to the network server, the redirector enables the word processing
program to become a network client.
List at least three redirectors.
1. Apple File
Protocol
2. NetBIOS Extended
User Interface (NetBEUI)
3. Novel IPX/SPX protocols
4. Network File
System (NSF) of the TCP/IP suite
What is meant by a “client-server” environment?
the client is a local computer (requester of services), the server is a remote computer that provides those services requested by the clients. It is the usual networking model.
What is indirect-application network support?
it is a client-server function. It allows the redirector to send files from a client to a remote server.
What assigns logical names to resources on a local client? What allows this to happen?
The network administrator assigns logical names to remote resources (such as printers). These resources are local clients. The network redirector is what actually allows this to work. It sends the selected file to the proper remote resource on the network for processing.
How does a redirector process transactions such as connecting to a server?
It connects only long enough to do the processing, then it terminates the connection. The connection must be reestablished each time the resource is requested.
What is a domain name? What is the maximum number of characters allowed in a domain name?
It is a way to map a string of characters to an IP address. The max characters allowed (right now) is 64.
What is the domain name server? What does it do?
The Domain Name Server manages the DNS entries and what IPs they stand for. (It maps names to IPs.) It is a device on the network that responds to client requests for DNS service.
What is the most commonly used application on the Internet?
World Wide Web (WWW)
Name some other applications on the Internet:
1. Telnet
2. FTP
3. e-mail
4. Network
information gathering and monitoring applications (SNMP, for example)
What are the two parts of an e-mail address? Which part must be unique to the mail server?
What must you have in order to access your e-mail account?
a password
What do we mean by “store and forward” technology?
files are stored on a server until they are “called” for. Then they are forwarded to the owner. This is how e-mail works.
Where are e-mail messages stored until they’re called for?
they are stored in a “mailbox” on the mail server.
What is the common mail protocol used to receive (download) e-mail messages?
POP3 (Post Office Protocol)
What is the common mail protocol used to send (upload) e-mail messages?
SMTP (Simple Mail Transfer Protocol)
Where does processing take place if you are Telnetted into another computer?
When you Telnet to another computer, your computer becomes a dumb terminal; all processing takes place on the remote computer.
What layers of the OSI model does Telnet work at?
7, 6, 5
What is FTP? What is it designed to do?
File Transfer Protocol – it allows you to upload or download files to/from a remote location. The main purpose of FTP is to transfer files from one computer to another by copying and moving files from servers to clients, and from clients to servers.
What is HTTP?
What is a web browser?
a client-server application that interprets data in multimedia formats (use text, graphics, sound, and video) on Web pages
What is a hyperlink? Where would you typically find one?
an object (word, phrase, graphic) on a Web page that, when clicked, transfers you to a new Web page. You typically find them on Web pages.
What is a URL?