DoS and DDoS Attack: A Beginner’ Guide in 4 Easy Steps


The internet has been both a boon and a bane at the same time. Connecting across the globe has reduced the distance between places and opened up our systems for attacks from malicious unknown characters. Keeping our data safe from faceless cybercriminals has become essential. Our data has to be secured from these hackers. The cybercriminals use various ways to hack a system. In this article, let’s take a peek at how cybercriminals use Denial of Service (DoS) and Distributed Denial of Service (DDoS) methods to hack systems in organizations.

  1. What are DoS and DDoS attack?
  2. Difference between DoS and DDoS Attack (Dos vs. DDoS)
  3. Types of DoS and DDoS attacks 
  4. How to prevent DoS and DDoS attacks?

1. What are DoS and DDoS attack?

DoS and DDoS attacks are the two most terrifying threats faced by organizations today. 

Denial of Service (DoS)

A DoS attack is a denial of service attack wherein the victim’s computer is bombarded with traffic from the hacker’s system. The attack is such that the victim’s computer shuts down. While attacking, the focus is to burden the victim’s server affecting its capabilities forcing the computer to shut down. DoS attack is an online attack. When the attack is made on a website, it is made completely unavailable for its users. The target web site’s server is bombarded with huge traffic from hackers’ system to shut its services.

Distributed Denial of Service (DDoS)

A DDoS attack is a distributed denial-of-service attack wherein the victim’s computer is bombarded with traffic from multiple systems across different locations. The focus is to burden the victim’s server such that it stops working as expected. If it is a network, the server becomes inaccessible to all its users.

Both attacks focus on making the victim’s computer or server unavailable. In short, they isolate the system from their connected devices. So, what is the difference between DoS and DDoS attacks?

2. Difference between DoS and DDoS Attack (Dos vs. DDoS)

Denial of Service (DoS) Distributed Denial of Service (DDoS)
A single system targets the victim’s computer. Multiple systems target the victim’s computer.
The victims’ system is loaded from the data packet sent from one single location. The victims’ system is loaded from data packets sent from multiple locations.
DoS attack is comparatively slower. The DDoS attack is faster than DDoS.
The victim has a chance to block the hacker’s system. It is challenging and daunting to block as the attack is from multiple systems from multiple locations.
A single device with DoS attack tools is used.  Bots are used to attack at the same time.
The volume of traffic in the DoS attack is comparatively less than DDoS. A massive amount of data is sent to the victims’ system or network. 

3. Types of DoS and DDoS attacks       

Here are a few commonly used methods of DoS and DDoS by hackers.

Types of DoS attacks

  1. Buffer overflow attacks

Buffer overflow vulnerabilities are commonly used by hackers to gain access to the victims’ computers. Buffer is part of the memory allocated to store data. Buffer overflow happens when more data flows, and the system is unable to handle. The additional data flows to adjacent memory space, thereby corrupting data previously in the space. This results in a system crash, creating a path for the hacker to initiate his/her malicious actions.

2. Volumetric Attacks

Volumetric attacks are focused on the network’s bandwidth resources. As the target network bandwidth is consumed, it becomes completely unavailable to its connected devices. The attacker uses volumetric attacks on network devices with ICMP echo requests to an extent where the victim’s system bandwidth is no more available.

3. TCP-State Exhaustion Attacks

The hacker targets the webserver or firewalls wherein the number of connections is targeted. In TCP-State Exhaustion, attacks are to push the target server to the maximum limit of connections.

Types of DDoS attack

  1. Ping of Death

In the Ping of Death attack, the hacker attacks from multiple locations to one computer. POD attacks send packets of data bigger than the maximum packet length. These packets are sent in fragments. The victim’s server gets engaged to assemble these fragments as the victim’s server network resources are completely used up in assembling fragments. This process completely shuts down the victim’s server and makes it unavailable to other devices.

2. UDP Floods

A DDoS attack that bombards the victim’s network with User Datagram Protocol (UDP) packets. The ports are flooded in the target server. The target server keeps looking up for an application listening to the port. When the application is not found, it replies packet that the destination was not reachable. This process consumes resources in the network, which makes it unavailable to other devices’ connectivity.

3. SYN Flood

In this attack, the attacker uses TCP connections to make the victims’ networks unavailable. On receiving the SYN request from the attacker, the victim’s system sends back the SYN-ACK response. The attacker ignores to respond with ACK response. The victim’s requests go unanswered, thereby consuming the network’s resources. The network is left with no resource to make a new connection with any other connected device.

4. How to prevent DoS and DDoS attacks?

DoS and DDoS attacks are a constant threat to organizations today. By undertaking safety measures, you can protect your servers from attack. The key is to protect the infrastructure from successful attacks.

The steps taken by the organization to minimize the damage from attacks are:

  • Precautionary measures for network protection.
  • Running test DOS Attacks.
  • Response Plan on Attack.

Regular monitoring of the network is a precautionary measure taken across the organizations—this aids in identifying the attacks and take necessary precautions. By regular monitoring traffic, one can identify any unusual data traffic from unknown IP addresses. Normally, attackers test the system before launching a full-fledged attack. 

Not all DoS attacks can be prevented. The best way is to test our precautionary measures in place by simulating the DoS and DDoS attacks in the network. Simulating the attacks will test the prevention methods and aid to design strategies for attacks.

By any chance, if the attacker has succeeded in hacking, a response plan in place will aid know the damage control. A clear plan with designated roles can get the system up and running in no time. At the same time, the team can access the damage too.


Now that you have a detailed insight regarding dos ddos, here’s some common reasons found behind these attacks are Ransom, Competition, and Hacktivism to name a few. As per the recent survey first half of 2020 has witnessed a 4.83 million DDoS attack. The attacks during COVID times are on healthcare, e-commerce, educational services. The recent attacks are complex, speedy, and the duration of the attack is very small. The sophisticated attacks are posing a challenge to cybersecurity experts across the globe. Organizations are investing heavily in cybersecurity personnel and infrastructure to keep their data safe from these cyberattacks. Security professionals are vigilant to protect data that is enabling our modern world.

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