DoS vs DDoS Attack: What Is the Difference?

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Cyberattacks are evolving rapidly, and Denial-of-Service (DoS) and Distributed Denial-of-Service (DDoS) attacks remain two of the most disruptive and damaging types of cybersecurity threats to websites of all kinds. While they may seem similar, their methods, scale, and impact vary massively. Understanding the difference between DoS vs DDoS is essential to having a head start when it comes to preventing and mitigating them. This guide explains these attacks, what sets them apart, and how to stay protected with the right tools and Web Hosting.

KEY TAKEAWAYS

• DoS attacks are usually launched from a single origin, making them easier to trace and defend against.
• DDoS attacks use massive numbers of devices to flood systems, making them more difficult to detect and mitigate.
• The complexity, size, and automation behind DDoS attacks make them exponentially more dangerous than DoS attacks.
• Proactive, layered defenses are essential to stop or mitigate the impact of DoS and DDoS attacks.

What is a Denial of Service Attack?

A Denial of Service (DoS) attack is designed to make a website, server, or network unavailable to legitimate users by flooding it with a large number of malicious traffic requests, thereby overwhelming and causing it to either crash, or slow it down to the point of being unusable. This not only hurts your website visitor experience, but also your search engine rankings.

These attacks originate from limited or single sources, making them relatively easier to identify and block. However, because of IP spoofing, finding source IP addresses can make it difficult to trace the attack back to its actual origin.

Types of DoS Attacks

• Buffer Overflow: Exploits memory limits to crash systems. Hackers send too much data to a program, which “spills over” and can crash the site or let hackers run their own malicious code.
• Ping of Death: Sends oversized or malformed data. The victim’s system is unable to reassemble these corrupted packets correctly, which causes them to crash or freeze systems.
• Teardrop: Similar to the Ping of Death, this also sends fragmented data packets with confusing information about their order that devices can’t reassemble, causing the receiving computer or server to freeze or crash.
• SYN Flooding: The attacker sends multiple fake connection requests (SYN packets) to a server, but never finishes the connection. This exhausts web server resources, making it unable to handle real requests.

An example of how DoS attacks are launched is the Low Orbit Ion Cannon (LOIC). This is considered an “entry-level” tool because it’s easy to use and doesn’t require advanced technical skills like some other methods. For example, hackers can use LOIC to flood a target server and network devices with HTTP requests.

What is a Distributed Denial of Service Attack?

A Distributed Denial of Service (DDoS) attack is a DoS attack on steroids. It uses multiple systems often organized into a botnet to overwhelm a target server, network, or site with traffic.

A botnet is a network of private computers infected with malicious code and controlled as a group without the owners’ knowledge. These bots or zombies are often used to launch large-scale attacks, send spam emails, or spread malware.

Because the traffic comes from hundreds or even thousands of sources and IP (Internet Protocol) addresses, this type of attack is much harder to block, trace, and stop.

“DDoS attacks are becoming increasingly sophisticated as adversaries evolve their attack patterns, botnets, and other technologies,” says Ivan Shefrin, Executive Director of Managed Security Services at Comcast Business. (Source – Cyber Magazine)

Types of DDoS Attacks

• Volumetric attacks, like a User Datagram Protocol / UDP flood, overload a network layer with massive, sudden traffic spikes from a range of IP addresses, consuming all available bandwidth and making it impossible for legitimate network traffic to pass through.
• Protocol attacks, like SYN and ping floods, target weaknesses in communication protocols by sending excessive Transmission Control Protocol (TCP) connection requests. The goal is to exhaust network resources for devices, such as Web Application Firewalls (WAFs) or load balancers, rather than just the server itself, making it unable to handle new, legitimate connections.
• Application Layer attacks are more subtle and target specific software or web applications rather than the entire network. An attacker sends a high volume of seemingly legitimate requests to a web server. These requests can be for complex tasks, like searching a database that consumes a lot of server resources. Because the requests appear normal, they are harder to detect, and the server gets overwhelmed trying to process them all.

It’s worth mentioning that application-layer DDoS attacks have increased by 74%, focusing on websites, APIs, and login pages, particularly in the financial, ecommerce, and ICT (Information and Communication Technology) sectors.

DoS vs DDoS Attacks

While both aim to disrupt websites, the main differences between DoS vs DDoS lie in their scale, origin, and complexity of the attack vectors.

A DoS attack comes from a single source and usually uses (comparatively) simple methods to flood or crash a server or site. Since the traffic originates from a single location, these attacks can often be blocked using basic firewalls and filters. The single origin makes detection and defense generally easier.

A DDoS attack, however, involves multiple sources, often spread across different geographic locations, forming a botnet. These coordinated DDoS botnets, often combined with amplification techniques, send huge, simultaneous waves of traffic that are much harder to stop. The use of compromised systems and spoofed IPs makes it difficult to trace the attack’s true origin. Due to their size and distributed nature, they require more advanced tools to mitigate.

Common Signs & Symptoms

If your website is under attack, there will be signs. Knowing what the red flags to look for are and responding quickly can help minimize the damage and avoid extended downtime.

The most obvious symptom is that your site suddenly slows down or crashes completely. Pages may take a long time to load, if they load at all, and visitors may see a “Server Not Responding” error in their web browsers.

On the technical side, one of the first signs you’ll see is unexplained spikes in bandwidth usage. This is because the malicious traffic eats up all of your available network connection capacity, leading to slow loading speeds and potential crashes mentioned above.

Another major red flag is a big traffic spike from multiple locations or IP addresses, causing slow network performance. Legitimate web traffic can spike, which can be a good thing for your online business (provided your web hosting can handle it). However, the sign you’re under attack is when it has a suspicious pattern, with a large number of requests coming from multiple sources and IP ranges simultaneously.

Finally, checking your server logs will show identical or malformed requests. Attackers often send large amounts of the same type of request or send malformed packets that the web server can’t process correctly.

Which is More Dangerous DoS vs DDoS?

The short answer is that DDoS is vastly more dangerous and damaging than DoS for three main reasons: scale, complexity, and deception.

As we’ve already covered, a standard DoS attack originates from a single source, which can usually be identified and blocked quickly.

On the other hand, because DDoS attacks come from a botnet, the attack traffic is a flood from thousands or even millions of different sources. The sheer volume of traffic from a DDoS attack can easily overwhelm WAFs, intrusion detection systems, and other security features.

DoS attacks are also generally easier to identify. The traffic comes from one place, so it’s relatively easy for basic firewalls and network filters to spot and stop the suspicious activity. The source IP address is usually visible, too, making it easier to trace and report.

DDoS attacks are far more complex. The traffic comes from a wide range of devices and source addresses, often appearing to be legitimate requests. Attackers use sophisticated methods to coordinate botnets, making them harder to distinguish from normal user activity and filter malicious internet traffic.

They are also inherently deceptive, as they use compromised or zombie devices and spoofed IP addresses to hide their location while causing widespread damage. The decentralized and anonymous nature makes it extremely difficult to find the source, making it a much more dangerous and persistent threat.

To illustrate just how dangerous they are, in Q1 2025, Cloudflare blocked over 20.5 million DDoS attacks, representing a 358% year-over-year increase. (Source – Cloud Flare Blog)

The largest DDoS attack ever recorded occurred in mid-May 2025, reaching a staggering 7.3 Tbps (terabits per second), flooding the target with 37.4 TB of data in just 45 seconds. (Source – Cloud Flare Blog)

Ashley Stephenson, Chief Technology and Product Officer at Corero Network Security, stated in their Threat Intelligence report:

“DDoS is no longer just a matter of stopping network packets—it’s about identifying patterns, coordinating teams, and mitigating before damage is done. We see a growing gap between how attackers operate and how defenses are organized. Bridging that gap is essential.” London, UK – May 7, 2025 (Source – Corero’s Blog)

In an even more worrying development, advances in agentic AI technology are allowing even novice attackers to graduate from simple DoS attacks to coordinating DDoS campaigns relatively easily.

This is highlighted by the Nexusguard 2025 Trends Report, which states: “Despite the rise in massive attacks, 85% of DDoS attacks remain under 1 Gbps, showing attackers’ preference for short-burst, small attacks that evade detection” – Singapore, Jun 10, 2025 (Source – Nexus Guard Blog)

Additionally, variations involving Internet of Things (IoT) devices are another attack method being used.

IoT devices, such as smart cameras, routers, and even home appliances with network connectivity, often come with security vulnerabilities, including default passwords and unpatched firmware. This makes them easy targets for hackers to infect with malware, turning them into part of a botnet.

Volumetric DDoS attacks using compromised devices have been responsible for record-breaking network bandwidth volumes, with one attack reaching 5.6 Tbps in late 2024, using a DNS amplification technique.

We’ve officially reached the stage where your new smart refrigerator can be used for evil.

Even more shocking is the rise of DDoS-for-hire. Groups like KillNet and Anonymous Sudan have evolved into for-profit cyberwarfare mercenary outfits, with 17% of the people behind attacks providing this “service”.

As you can see, they’re no longer rare events; they happen almost constantly, they’re well-coordinated, and often politically or financially motivated.

How to Mitigate DoS And DDoS Attacks

Knowing how to defend against these attacks is essential for keeping your online business service availability up and running. The mitigation strategies you use will depend on the issue you are dealing with.

Starting with the easier of the two to manage, depending on the type of DoS attack, they can often be stopped with fairly standard website security features and tools.

Firstly, monitoring your website’s traffic will help you get a head start. Regularly checking for unusual spikes from a single IP address or area can be an early warning sign that you’re under attack.

Next, firewalls sit in front of your website and server, filtering out harmful traffic. They can identify and block requests, like those used in buffer overflow attacks, before they reach you. WAFs can also act as a reverse proxy, protecting the target machine from certain types of malicious traffic, so ensure you have one.

Finally, rate limiting restricts the number of requests a single IP address can make in a certain timeframe. It’s an effective way to prevent a DoS flood from eating up your server’s resources.

As we’ve already discussed,DDoS attacks are more difficult to stop due to their size and distributed nature, so they need more advanced methods.

Cloud security services like Cloudflare and AWS Shield are designed to handle massive spikes. They work by absorbing and scrubbing malicious traffic before it ever reaches the server or your site.

You can also set up filtering and geo-blocking to prevent traffic from specific countries or regions known to be high-risk, thereby reducing the potential for attack.

Web Hosting Security from Hosted.com®

They say the best defense is a good offense. Hosted.com® offers a suite of features to protect your website. Built-in DDoS protection automatically detects and filters harmful traffic before it can reach your server, ensuring your site remains available even during a large-scale attack.

CageFS Security, developed by CloudLinux, is a virtualized system that “cages” each site into its specific private environment, preventing cross-contamination and preserving system resources in case one site on the server is attacked.

A WAF acts as a shield for your website, inspecting incoming requests and blocking common web-based attacks, such as SQL injection, brute force attacks, and cross-site scripting, before they can cause damage.

Imunify360 is a comprehensive, automated server security suite. It includes a WAF, an antivirus scanner, intrusion detection and prevention systems (IDS/IPS), and a tool for patching vulnerabilities, all working together to protect your site from malicious attempts to gain access.

To back this up, we offer a 99.9% uptime guarantee, ensuring your website remains available to visitors 24/7. This protects your online business from the financial and reputational damage that downtime can cause, giving you peace of mind.

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