What is IP Addresses? URL’s, ?File Transfer Protocol (FTP)

IP Addresses

AN IP address is a numeric identifier assigned toeach machine on an IP network. IP address is a software address, not a hardware address, which is hard coded in the machine or NIC. An IP address is made up of 32 bits of information. These bits are divided into four parts containing 8 bit each. The 32 bit IP address is a structured or hierarchial address. The network address uniquely identifies each network. Every machine on the same network shares that network address as part of its IP address. The IP address 121.45.67.45, the 121.45 is the network address and 67.45 is the node address. The node address is assigned  to and uniquely identifies, each machine on a network. The router might able to speed a packet on its way after reading only the first bits of address.

Hosts

Each host on the internet has a unique TCP/IP address, which is four numbers separated by dots. An example address is 123.45.54.32 which is the TCP/IP address of a computer.The TCP/IP address known as a physical address. All the four numbers will be in the range 0-256. These don’t mean much to users, so logical names are allocated to host computers as well, 123.45.54.32 may also be known as xli.cet.ac.au. Communication is established between a user and da host computer by using the TCP/IP address. Data is sent from the user with the destination address being as the host computer. The host computer, when sending data back to the user, specifies the destination address of the user.

Servers

Servers are host computers which provide a service to users. An example of server’s service could be the storage and retrieval of files and documents. Other types of servers are www (world wide web) servers, ftp (file transfer protocol) servers, gopher servers, mail servers and news servers. Each server uses a specific protocol or method of communication based on TCP/IP. For example, www servers use the HTTP protocol, mail servers uses SMTP protocol, and news servers use NNTP protocol.

Hyper-links

An hyperlink is a clickable link to another document or resource. It is normally shown in blue underline. When a user clicks on this link, the client will retrieve the document associated with that link, by requesting the document rom the designed server upon which it resides.

Example of hyperlink : http://www.simplinotes.com/

URL’s

A uniform Resource locator is a means of specifying the path name for any resource on the internet or an intranet. It consists of three parts:

A protocol

A host part

A document name

For example : http://www.cet.ac.nz/smac/ckware.htm  specifies he protocol as http, the host or www server as www.cet.ac.nz and the document as /smac/csware.htm.

File Transfer Protocol (FTP)

File Transfer  Protocol  service  (known  as FTP  in short) enables  an Internet  user to move a file from one computer to another  on the  Internet.  A file  may contain  any type of digital  information   –  text  document,   image,  artwork, movie,   sound,   software,   etc.   Moving   a  file  from  a  remote   computer   to  ones  own   computer   is  known   as downloading  the file, and moving  a file from ones own computer  to a remote  computer  is known as uploading  the file.

By using FTP service,  a file transfer  takes place in following  manner:

1. A user  executes   the ftp   command   on  his/her   local  computer,   specifying   address   of  the  remote computer  as a parameter.
2. An FTP process running  on user’s  computer  (called  FTP client process establishes     a connection  with an FTP process  running  on remote  computer  (called  FTP server process).
3. The system  then  asks  the user  to enter  his/her  login  name  and  password  on the  remote  computer  to ensure that the user is authorized  to access the remote computer.
4. After successful login, desired  file(s)  are downloaded  or uploaded  by using get (for downloading)  and put  (for  uploading)   commands.   User  can  also  list  directories,   or  move  between   directories   of  the remote computer,  before  deciding  which file(s) to transfer.