Q) Explain briefly about Telnet and Remote Login:-
Telnet
and Remote log-in are two programs that allow you to log-in to another
computer. These two programs allow you to use and interact with software which
is the remote mission. To do this user needs second computer account that is
accessible. This second computer is usually at a different physical location
hence the phrase “Remote-long-in”.
Telnet: The
Telnet command uses the Telnet protocol to log-in to a remote computer on the
Internet. A wide range of Telnet clients provide user friendly interfaces. One
of the ways of invoking Telnet illustrated in the below figure
A
Telnet client can usually be launched from one of the systems menu simply by
selecting the telnet option, then the above interface appears through which
user can select the remote system option. On UNIX systems, user can type the
command and receive the telnet prompt “telnet >”. The host name is the
machine domain name or the numerical address of the machine. Once user
specified the host name and establish a connection user can log-in and begin
executing commands on the remote machine. It is usually necessary to have an
account on the remote system in order to telnet /connect to it. However some
systems allow “guests” to access their database without account (anonymous).
The
rlogin command is similar to Telnet except that it provides the remote computer
with information about where you are logging-in from. On the Unix systems the
list of host names is given in a hidden file called “rhosts”. As with Telnet,
once you are logged into a remote machine you will not be able to execute
commands using your own local log-in sessions. So, as a conclusion Telnet is a
more secure remote log-in mechanism than rlog-in.
Q) Describe briefly about FTP (File Transfer Protocol)
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“File
Transfer” is an application that allows you to transfer files between two
computers on the Internet or on the same network. Following two most important facilities
provided by File Transfer application.
1. Copying a file from another computer to your computer
2. Sending a file from your computer to another computer
Below figure illustrates the idea of the File Transfer
process
File
Transfer is the fastest and most convenient method to transfer file, however
there are other ways of copying a file from one computer to other. For example
if the file is not too large, You may be able to e-mail the file to an account on
the second machine.
Graphical File Transfer Files:-
Graphical
File Transfer clients are the easiest to use. These applications display the
sending computer’s file system in one window and the receiving computer’s file
system in a second window as shown in the below figure. In this scenario you
first need to login to each computer to prevent unauthorized File transfers. To
transfer a file from one system to another you can “drag” using mouse and drop
it on the destination system. One important point is the transfer setting mode,
which can specify by clicking on a button. Most FTP clients have a “text
transfer mode” and a “binary transfer mode”. Mode should be set to binary when
transferring images.
Text based File Transfer clients:-
Along with graphical systems there are text based file transfer
clients. For example you can launch the UNIX FTP client by typing following
command % ftp hostname
Host
name is the name of the computer with which you want to exchange files. Once
you have successfully initiated on “FTP” session you will be greeted by the
prompt ftp:>. At this prompt can enter the following commands, to
transfer the files.
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Command
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Description
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1
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Bye
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Terminate the ftp
session
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2
|
Cd
|
Change directory
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3
|
Get
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Copy a file
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4
|
Help
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View list of
commands
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5
|
ls
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List the files in
current directory
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6
|
Put
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Send a copy of a
file
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7
|
pwd
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Print the name of
the current directory
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File Compression:-
It is wise to compress files
which need to be transferred between two computers via network because
compressing a file makes it smaller and can be transferred quickly.
A wide variety of
compression tools are available for example
1. Compress
2. gzip
3. pkzip
File extensions will usually
alert you to whether or not the file is compressed. Ex. “.z” (compress),
“.gzip” (gzip), “.zip” (pkzip).
You
need to decompress the file to use it i.e., one must use the appropriate
decompression tool which depends on how the file was compressed. There are
number of web sites from which you can download compression and decompression
programs. File compression is on extensive field in computer science and
algorithms used are very interesting.
Q) What do you mean by Computer Viruses? Explain it.
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Definition: “ A virus reproduces, usually without your
permission or knowledge. In general terms they have an infection phrase
where they provide widely and an attack phrase where they do what ever damages
they are program to do, (if any)”.
“A
virus is a program, that reproduces its own code by attaching itself to other
executable file in such a way that its code is executed when the infected file
is executed. viruses coming in many types using many different infecting
strategies”.
Viruses can infect
a no. of different portions of the computer operating and the file system. This
includes
1. System sectors
2. Files (data, image etc)
3. Macros
4. Companion files
6. Batch files
7. Source code
8. Works – using vb code
Safe computing practices:-
1. Update anti-virus software
2. Safe boot disk
3. Hard disk boot
4. Use “rtf” (rich text format) not doc format
5. Consider alternate software
6. Don’t open attachments (specially when they are from unknown)
7. Turn of preview
8. Disable scripting
9. Show file extensions
10.Protect medias (read-only)
11.Back-up copy, finally most importantly back-up.
Q) Explain briefly about News groups Fundamentals (1970’s).
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A News groups is a
discussion group in which computer users through out the world participate.
Users interested in a particular topic may subscribe to the related new groups.
Boundaries such as age, gender and background generally don’t play a role in
the discussion. Since users usually see messages only from each other. Some one
can e-mail a message called an article to the new groups at any time. The
message then becomes available for others to read. They can then respond to the
article, sharing their opinions are expertise i.e., a newsgroup is an
electronic form that allows users from all over the world to participate in a
discussion about a specific topic. There are currently billions of newsgroups
covering nearly every imaginable subject area.
Newsgroups
terminology:-
1. Article:- A message written and sent to a newsgroup.
2. Post:- Synonym for article.
3. Posting:- The process of sending an article to a
newsgroup.
4. Follow-up:- An article posted in response to a previous
newsgroup article (reply).
5. Thread:- A collection of one or more following articles
together with the original posting.
6. Subscribe:- The procedure you follow to add a newsgroups to
the list of those you read on regular basics.
7. Unsubscribe:- The process of removing a newsgroup from the
list of those that you read.
8.
News reader:- A program that serves as the user interface for
newsgroups i.e., this program allow you to read, post, subscribe and
unsubscribe from newsgroups along with other things.
9. News client:- A synonym for news reader.
10. Expired news:- News that is removed from a system, usually
after a short period time.
11. News server:- A computer that saves, forwards and manages
news articles.
12. Newsfeed:-
A news server that provides recent articles to a news client.
13. Ways station:- A news server that functions as a newsfeed for
atleast two other sites.
14. Network News transfer protocol (NNTP):- The
protocol used for distributing news articles.
15. News administrator:- A person who is in charge of running a news
server.
16. News Moderator:- A person associated with the specific newsgroups who reads and
critically evaluates all articles submitted for posting.
17. Moderated News group:- A newsgroup that has a moderator.
18. Unmoderated Newsgroup:- A newsgroup that has no moderator.
19. Cross post:- The process of submitting the same article to
two or more newsgroups.
20. Digest:- A collection of related articles.
21. Kill files:-
A filter – based on names or topics that you specify.
Q) Write a Short Note on News Reader:
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A newsreader is a program which serves as the
user–interface with news-groups
As shown in the
above figure, the functionality of the graphical buttons make reading the news
vary easy. In the past, most newsreaders were keyboard driven and unfriendly by
today’s expectations. Now, many web browsers have built-in newsreaders. Which
makes reading news much more enjoyable and interacting process. Hyperlinks can
be followed write from with in a news article.
Netscape newsreader
as shown in the above figure divides the screen into several panels. It also
allows you to resize the relative proportions of the panel. It provides several
pull-down menus with the headings “file”, “edit”, “view”, “go”, “message”, “communicator”
etc. as in customarised menus, menu items that are not available for the
current configuration are shown in a lighter gray color. It also includes
several numbers of buttons, which are self-explanatory. The most commonly used
once are
1. “post” a new article
2. “send” e-mail
3. “reply” to e-mail
4. “reply” to a posting
The next part of
the news window is divided into two sections on the top is the name of the news
group and a list of the messages with their subjects. If you click-on one of
the articles, it will appear in the bottom part of the screen as shown in the
above figure. An article can contain hyperlinks.
Reading news:- Reading news is very easy in a text based news
reader, you need to simply enter the number or a name of a news group
and then entering the number of the article you want to read. In a graphical
newsreader all you need to do is select a news-group and then select an article
from with in the news group. Since the number of news groups is so vast a lot
of interesting information can be found in news-group. But it can some times be
time consuming to locate. “PEJA” news will you to filter the news and to locate
based on your interest.
Posting news:- Once you have been reading a newsgroup for a
while, you will obtain a sense of what types of postings are appropriate
for the group. So, take care in composing the message and don’t post unless you
have something work while. When generating an article follow the netiquette
rules.
Keeping track:- News readers maintain a data file often name
“Newsrc” when you subscribe to a news group on entry is put in this
file. When you read a posting the ID information is updated in your
subscription file with the help of subscription file content the newsreader
keep you uptodate.
Q) Describe briefly about Newsgroup Model.
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Newsgroups model:- There are three methods by which news can be distributed
An illustration of how News Articles are propagated throughout the
world
1. News push
2. News pull (news suck)
3. News search
In news-push the news is delivered without
being specifically requested. At a basic level in a news-push, a news-feed
contacts its client and indicates that it has new articles. The client must
respond by telling the news-feed with article it wants.
In news-pull, the client requests the news
and as if delivered i.e., a news client contacts one of its news feeds and asks
if there are new articles. The news-feed response by listing the new articles,
then client must determine which article it needs and make a request to
retrieve those.
The third method of
news distribution is called news- search.
DEJA news is a search engine that specializes in news-groups i.e., instead of
subscribing to newsgroups it easier to search and browse deja news. It has a
larger collection of newsgroups and the postings available of different
newsgroups. It also offers powerful search options to request a profile of all
the news groups. This visibility or transferency is revolutionary.
Q) Explain briefly about Mailing List
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Mailing Lists Fundamentals:- An mailing list is a group of users with a shared
interest whose e-mail address are collected together in an electronic list,
that can be use to send e-mail to each member of the list. The key to mailing
list is a program called a “List Server”, which receives and distributes
postings. This program also automatically manages subscriptions.
