What is a DoS attack?
A DoS attack means a Denial-of-Service attack, which happens when a single hacker attacks a single target computer. So, one computer and one Internet connection is used to flood the server with packets. The cybercriminal sends in a large number of legitimate-looking requests to the server in a way that the server really cannot distinguish between viable and non-viable request. It will swamp the system to a point that the server cannot handle the capacity anymore.

The DoS is a very powerful attack in which the cybercriminal makes the system or data unavailable to someone who needs it. The distributed attack happens when one hacker takes control of many computers and makes the system or data unavailable to someone who needs it.

There are several types of DoS attacks that can be carried out. They are:

• Flooding the network to restrict legitimate network traffic
• Obstructing the connections between machines, thus preventing access to a service
• Barring a particular individual from accessing a service
• Disrupting a service to a particular system or individual
• Disrupting the state of information, such as resetting of TCP sessions

Risks involved with DoS attacks
The Denial-of-Service attacks are focused to ultimately crash the system by overburdening the target’s resources. For example, a web server provides a service for hosting web pages, there are the web pages created using HTML, which reside on a web server. The users use the HTTP protocol in the browser to request a webpage from a web server. The request goes through the Internet to the web browser which in turns sends us the .html file that we view on our web browsers. When the DoS attacks the web application, the software is overburdened and fails to serve web pages rightly. To crash the server, the hackers attack the following services:

• Database connection pool
• Server memory
• Network Bandwidth
• CPU usage
• Database space
• Hard disk space
• Application exception handling mechanism

Business people and IT professionals were not really aware of the reason behind such Denial-of-Service attack, they failed to consider that it was a kind of protest by the hackers. However, recent study reveals that the Denial-of-Service attacks can turn out to be a platform for the hackers to make profit.

If you do not proactively work to stop the Denial-of-Service attack, you may leave your computer vulnerable to:

• Financial losses : The websites which deal with doing business online are more prone to DoS attacks as it is more profitable for the hackers. The damage results in a huge revenue loss.
• Brand damage : The hackers usually target to damage the reputation of the brand. It would make the users feel insecure and the brand would literally lose its genuine customers.
• Sabotage : Deliberate damage to the business website to construct a stronger market share.
• Extortion : Hackers force or threaten to disrupt service until they obtain money.
• Other attacks : The data and information collected by the hackers from the DoS attack can be retained to further attack a website later on. Moreover, the data can also be distributed and used to access more than they had originally planned.

How to prevent DoS attack?
By installing a security web application like Not Defender, Veracode, Imperva Incapsula can help you prevent Denial-of-Service attack because these firewalls would check the HTTP traffic and their packets and decide whether or not to allow IP address, ports, and protocols to prevent web application from being attacked. They provide full coverage from emerging hacking attacks and guarantees to mitigate and DoS or DDoS attack in under 10 seconds regardless of its size and without getting in the way of legitimate traffic.