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DoS attack, DDoS attack
Updated on 17th Mar, 23 419 Views

Through this blog, you will learn the following about DoS and DDoS attacks.

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What is a DoS attack?

The first step to understand the difference between DoS vs DDoS attacks is to understand what is a DoS attack (Denial of Service attack). The following section will elucidate the same.

In a Denial of Service attack, a site or server is filled with overwhelming or inorganic bot traffic by a third party. The third party is usually an attacker with malicious intentions.

The overwhelming traffic can be generated up to several gigabytes per second.

Every site or server is built with a certain level of hosting capacity and traffic is generated to exceed this limit. When the limit is exceeded, organic or real users have trouble accessing the site; the access is denied or the server or site crashes.

The generated inorganic traffic usually comes with no return address and, thus, makes the resolving time longer. This is because without a return address, the server or site cannot send authentication certification to verify the source. It is important to note that the traffic continues to accumulate until the same is resolved completely by the host.

A DoS attack has an upgraded version in the industry as well; this is known as a DDoS attack. The following section will briefly elucidate on what is a DDoS attack.

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What is a DDoS attack?

The next step to understand the difference between DoS vs DDoS attack is to understand what is a DDoS attack (Distributed Denial of Service attack). The following section will elucidate the same.

A DDoS attack is similar to a DoS attack but differs slightly. The difference between DoS and DDoS attacks is that, usually, a DDoS attack happens from multiple resources, while a DoS attack happens from a single IP address. Furthermore, the difference between DoS and DDoS attacks is evident through the intention of the attack. A DoS attack happens intentionally, while a DDoS attack can happen without malicious intention as well.

For example, if a page becomes popular overnight, it could witness heavy user activity. And when the user traffic is more than the site’s capacity, the page could crash leading to the organic users having trouble while accessing the site.

This happens to small pages where the host has designed the site with limited capability. Large-scale business pages, especially shopping sites, experience crashes of the same nature when there is any sale.

Briefly, the difference between DoS attacks and DDoS attacks can be understood via the following section.

Difference Between DoS AND DDoS Attack

DoS AttackDDoS Attack
DoS attack is used to crash websites/ servers by sending across traffic beyond the processing level of the receiver host from one device..Single system is used to generate attacksThe level of severity is lowThe attack process is slowEasy to detect. Detection is done by tracing the attacker’s IP address.DDoS attack is used to crash websites/ servers by sending across traffic beyond the processing level of the receiver host from various devices..Multiple systems are involved in generating the attacksThe intensity of attack is higherThe speed of the attack is comparatively fasterIt is very difficult to trace the attacker

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Types of DoS and DDoS attacks

The next step is to understand different types of DoS and DDoS attacks. The following section will elucidate the same.

DoS attacks:

Denial of Service attacks are primarily of two types, application attacks and network attacks.

Application attacks

Application Denial of Service attacks, also called Layer 7 attacks, target the operations of the site or server. By generating traffic to the extent that the site or server can no longer process any new requests, and the operations of the site or server are forced to be stopped.

Network attacks

Similar to application attacks, network attacks generate massive targets toward the host site or server. Network attacks saturate the host’s bandwidth with bot or inorganic requests. Currently, network Denial of Service Attack are tackled with firewall configuration.

DDoS attacks:

Yo-yo attack

This is a type of Distributed Denial of Service attack that predominantly aims at cloud-hosted applications. The DDoS attacker generates massive traffic and invades space, and when the host outscales to handle the attack, the DDoS attacker stops the attack. The attack resumes the attack when the host moves forward from the attacked space.

Briefly, it can be said that once the host believes that the site is safe, the attack will resume and this cycle will continue. Yo-yo DDoS attacks result in financial issues for the host.

Advanced persistent DoS attack

Commonly known as APDoS, an advanced persistent DoS attack can last for weeks and generate over 50,000 TB of inorganic or bot traffic. The prolonged attack is achieved by creating a diversion by attacking other sources. This means that the attacker will target a main server or site and would attack other sites till the host cools off the countermeasures. By the time the host believes the attack to be gone, the attack would start again.

The following are the current common types of DDoS attacks.

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Common types of DDoS attacks

HTTP flood

When http gets or posts requests to enter into a server, network, or site with the motive to shut it down, it is known as HTTP flood Distributed Denial of Service attack. The requests appear to be legitimate and the attack does not require techniques such as malformed packets, reflection, and spoofing.

The attack reaches its maximum potential by forcing the server to allocate maximum resources to resolve all requests effectively.


When an attack enables a web server to attack another web server, it is known as slowloris attack. This attack is initiated by sending partial requests to the target site. When the server keeps such partial requests open, more attacks will be generated by the attacker toward the target till the maximum process level is reached by the server. On reaching the maximum process level, the site will begin to deny further requests including organic requests.

Currently, this is an advanced DDoS attack.

UDP flood

This attack is initiated by flooding UDP packets at random ports of the target site. When the host tries to locate or resolve the issue, it would not be found. When the attack and the unsuccessful resolve mechanism cycle continues, the attack will successfully sap the host’s resources. As a result, the site will be inaccessible to organic or real visitors.

It is important to protect your site and your organization’s network from such attacks.

But, how? The following section will elucidate various tips on how to prevent DoS and DDoS attacks.

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How to prevent DoS and DDoS attacks

The following suggestions will help you to prevent these attacks:

  • Invest in anti-DDoS and anti-DoS attack services that help in the recognition of such attacks by analyzing network traffic.
  • If you suspect or conclusively find that your company server is under such an attack, then contact your internet service provider and discuss whether such traffic can be rerouted.
  • Check if black-hole routing can be done; it is where the traffic is rerouted to a null route. This helps in protecting your site from crashes.
  • Develop a DoS or DDoS response plan. This is helpful for big organizations. The development of a DDoS response plan includes allotting a dedicated team for monitoring the security or potential of a DDoS attack in an organization.

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The major difference between DoS and DDoS attacks is the attacking source and intensity. Comparatively, the effect of a DDoS attack is more severe than that of a DoS attack. However, it is important to build strong counter mechanisms to protect your organization from such attacks.

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