What is a DDoS Attack?

A Distributed Denial of Service attack is aimed at exhausting server or communication channel resources and making a website inaccessible to visitors.

The attacker’s goal is almost always pragmatic — extortion, competitive sabotage or political pressure. The issue is especially relevant due to the rapid increase in the scale and frequency of attacks: according to Cloudflare's report for Q1 2025, the number of recorded DDoS attacks increased by 358% compared to the same period last year, and the peak load reached a record 6.5 Tbps, which is roughly comparable to the total traffic of a major provider.

For any business, even a minute of downtime means lost sales, worsened search rankings and loss of customer trust, so website owners need to build a multi-layered defense in advance.

How Does a DDoS Attack Work?

A DDoS attack utilizes a distributed network of devices, ranging from hacked servers to infected IoT devices, to simultaneously send a massive number of requests. The server cannot process them quickly enough, the queue grows, and regular users receive timeout errors.

The following key types of DDoS attacks are distinguished:

Volumetric Attacks

The goal of such attacks is to overload the network channel or server with a large volume of traffic, intending to occupy the bandwidth and block access for regular users. Examples include UDP flood, where numerous packets are sent to random ports, ICMP flood with continuous echo requests, and DNS Amplification, where DNS servers are used to send massively amplified responses to the victim.

Protocol Attacks

This type of attack exploits vulnerabilities in network protocols such as TCP, UDP and ICMP at the network and transport layers of the OSI model. Unlike volumetric attacks, they are not aimed at the channel but at exhausting server system resources, such as connection tables or memory. The most well-known variants include SYN flood, which creates incomplete TCP connections, and Smurf attack, which uses broadcast ICMP requests to generate multiple responses.

Application Layer Attacks

These attacks target interaction with web applications and services, mimicking regular user behavior on a massive scale. They aim to overload the server's computing power at the application level. Examples include HTTP flood with a large number of GET or POST requests, Slowloris, which keeps connections open using incomplete headers, and attacks on DNS servers that cause failures in the domain name resolution process.

Signs of a DDoS Attack

How to identify a DDoS attack? There are characteristic signs:

• sudden increase in latency without a rise in visitor numbers;
• sharp spike in requests from a single autonomous system (AS);
• packet loss on the external router;
• CPU or RAM load reaching 100% while serving static content;
• repetitive patterned URLs in logs;
• identical referrer values in HTTP requests.

Consequences of a DDoS Attack

The consequences depend on the resilience of the resource. For example, online stores lose on average up to 9% of revenue in the first two hours of downtime. SEO specialists record ranking drops due to 5xx errors received by search bots.

Added to this are unforeseen expenses — a bill from the CDN or provider for exceeded traffic, not to mention reputational risks that are difficult to quantify.

Methods of DDoS Protection

DDoS protection methods can be divided into three levels:

First, hardware and software solutions at the local level: high-speed NGFWs with rate-limiting features, IPS with anomaly recognition, kernel-level packet filtering (ipset, nftables), and load balancers that support automatic black-hole routing upon threshold exceedance.

Second, cloud traffic scrubbing services such as global CDN platforms, specialized scrubbing centers and IaaS provider offerings like AWS Shield Advanced; they reroute traffic through distributed nodes and drop malicious packets before they enter your segment — this method remains the most popular due to rapid scalability.

Third, organizational measures are important: you need to prepare a response plan in advance, assign responsible personnel, conduct regular training with simulated DDoS load, implement multi-factor authentication for admin panel access and sign an agreement with the hosting provider for emergency bandwidth scaling.

The choice of hosting also plays a significant role — a reliable infrastructure can withstand abnormal loads and quickly enable filtering. Qhost hosting is among such solutions and is considered one of the most resilient on the market, minimizing downtime risk even under attack conditions.

Choosing the Right Protection Strategy

Effective server protection against DDoS attacks is based on key questions that help determine priorities and form a budget:

• what volume of traffic is critical for business operations;
• what peak loads the current infrastructure can handle;
• whether SLA is provided at the internet channel level and what guarantees it includes;
• how quickly a switch to a backup platform can be made;
• what one minute of downtime costs for your project.

Answers to these questions help select the appropriate level of protection. For small sites like blogs, basic WAF and connection speed limit settings will be sufficient. Large projects such as marketplaces should consider a hybrid approach — local filtering combined with a cloud scrubbing center, which avoids dependence on a single provider and adapts to different attack scenarios.

FAQ

How much can early preparation for a possible DDoS attack reduce potential damage to a company?

Early preparation can drastically reduce potential damage from a DDoS attack. Having a response plan, configured protection systems and trained personnel can reduce downtime from hours to minutes, minimizing financial losses and reputational harm.

What organizational measures, unrelated to technology, can help minimize the consequences of a DDoS attack?

Organizational measures include developing a clear incident response plan that defines staff roles and responsibilities, as well as conducting regular drills and attack simulations. It is also important to have established communication with the hosting provider and protection service providers.

What is the key difference between detecting a DDoS attack at an early stage and responding to an already active attack?

The key difference is that early detection allows preventive activation of protective mechanisms, filtering malicious traffic before it overwhelms the system. Responding to an already active attack means the service is likely already experiencing disruptions, and efforts are focused on minimizing downtime and restoring operability.

What specific types of DDoS attacks pose the greatest threat to web applications working with large volumes of user data?

For web applications with large volumes of user data, the greatest threat comes from application layer attacks such as HTTP floods or API attacks. They mimic legitimate requests but in huge numbers, overloading databases and server computing resources responsible for data processing.

Besides financial losses and reputational damage, what other non-obvious consequences can a successful DDoS attack on an online service lead to?

Non-obvious consequences include increased operational costs for infrastructure recovery and scaling, decreased employee productivity due to the unavailability of internal resources, and a heightened risk of data breaches if the attack is used as a diversion for more targeted cybercrimes.