DoS Attack and Types—What is the denial of service attack in hacking?

A denial of service (DoS) is a type of attack where hackers try to avoid legit users from accessing a particular type of service. In a DoS attack, the hacker mostly sends some messages asking the server or network to authenticate the requests that contain false return addresses.

The server or network will not locate the return address of the attacker while sending the authentication approval, and it will cause the server to hold before closing the connection. Whenever a server closes the connection, the hackers send some more authentication messages with false return addresses.

This process of server wait and authentication will begin again, which will keep the server or network busy. So in this article, we will talk about what is a denial of service attack in hacking and how it can happen in different ways and how to prevent it.

How does DoS Attack Works?

A DoS attack can happen in many ways. The main types of DoS attack include:

  • Distracting the state of information, such as resetting the TCP sessions.
  • Disturbing a service to an individual or a specific system.
  • Preventing an individual from accessing a particular service.
  • Disturbing the connections between two different machines, and prevent in accessing a particular service.
  • Over-crowding the network or server to prevent legit network traffic.

There is also some other variant of DoS known as smurf attack. It includes emails with automatic responses if someone sends thousands of email messages with a false return email address to several people in an organization that has activated autoresponder on their email facility, so the initial messages sent can become more and sent to the false email address.

What is a Denial Service Attack in Hacking

If a false email address belongs to some person, it can overwhelm that individual’s account.

Denial of Service Attack(DoS) Attacks Issues

DoS attacks can cause several issues like:

  1. Connection Interference
  2. Interruption of network traffic
  3. Inaccessible services
  4. Ineffective services

Types of DOS

There are several types of DoS attacks:

1.Volumetric Attacks

It is a type of attack in which the entire bandwidth of the network is consumed, and the clients are not allowed to gain access to the resources. This attack is achieved by overcrowding the network devices like switches or hubs with several reply packets/ICMP echo requests, so the entire network bandwidth is consumed, and no other user can connect the network.

2.SYN Flooding

An attack in which the hacker comprises several zombies and continuously floods the target with different SYN packets. All the targets will be weighed down by these SYN packets, and they can go down, or the performance will be decreased drastically.

3.Fragmentation Attacks

This type of attack fights back against the reassembling ability of the desired target. Several fragmented packets are delivered to the target, which makes it tough for the target to reassemble them all. Therefore, access is denied to legit clients.

4.TCP-State Exhaustion Attack

In this attack, the hacker tears down and set up TCP connections and weighs down the stable tables, which causes a DoS attack.

5.Application Layer Attacks

The hacker can take full advantage of programming errors in the applications, which can cause a denial of service (DoS) attack. It can be achieved by sending several application requests to the desired target to exhaust the resources so that they are not available to any legit clients.

In this case, a programming error can buffer an overflow attack; if the memory allocated to a specific variable is small than the requested, then it can lead to the crashing of the entire application or memory leakage.


This type of attack is achieved by causing permanent damage to the hardware of the system by sending false updates to the hardware and making it completely unusable. The only solution to recover is by reinstalling the hardware.

How to Prevent DoS Attacks?

If you run an online business, then you might want to know more about DoS attack prevention.

The earlier you identify an attack, the quicker you can recover the damage. Below are some things that you can do to prevent DoS attacks.

Get Help recognizing attacks

Most of the companies use technology or anti-DoS services to protect their websites. It can help you to differentiate between DDoS attacks and legit spikes in network traffic.

Investigate black hole routing

Service providers use ‘black hole routing’ to divert the traffic into a null route, which is referred to as a black hole. It can help to prevent the network or targeted website from crashing.


Now that you are familiar with all the possible DDoS attacks, so you can use the steps mentioned above to protect your website from such types of attacks.

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