What is a Firewall?


Firewall is a key security technology in the modern network infrastructure.


” A Firewall is a software or Hardware system that acts as a barrier between an Internal network and and external network”.

Types of Firewall

There are two types of Firewall.

  • Hardware Firewalls
  • Software Firewalls

What is DOS?


DOS stands for Disk Operating System.

Popular DOS Commands

Following are some of the popular DOS commands.


The ATTRIB command is used to display and modify file attributes.


EDIT command opens a text editor utility that can be used to create new files or modify existing files.


FDISK command is used to create and manage Primary, extended and logical partitions on a Hard Drive.


DIR command displays the Disk’s volume label and serial number, a list of all files and sub-directories, file size, date/time of last modification, total number of files and folders and free disk space remaining on the disk.


ECHO command is typically used with other commands or in a batch file to display text on the screen.


VER command shows the version of Windows you are using.