Top 7 DDoS Types in 2025 and How to Prevent Them

• Primary Categories of DDoS Attacks
• Additional Types of DDoS Attacks

• Key DDoS Mitigation Strategies
• DDoS Mitigation with Radware

1. Volumetric DDoS Attacks

Volumetric attacks aim to consume all available bandwidth between the target and the wider internet. These attacks generate high volumes of traffic using amplification techniques or botnets to overwhelm the target infrastructure.

Examples:

• UDP flood: Sends large volumes of user datagram protocol packets to random or specified ports on the target. The victim must process these packets, often generating ICMP responses, which increases load and saturates bandwidth.
• ICMP flood (ping flood): Bombards the target with ICMP Echo Request packets, forcing the system to reply with Echo Reply packets. This consumes both outgoing and incoming bandwidth and system processing power.
• DNS amplification: Exploits open DNS resolvers to send small queries that result in large replies. By spoofing the target's IP address, the attacker redirects amplified traffic to the victim, significantly increasing the impact relative to the attacker's effort.

2. Protocol DDoS Attacks

Protocol-based attacks exploit vulnerabilities in network protocols to exhaust server or intermediary device resources such as firewalls, load balancers, or connection tables. These attacks typically aim at layer 3 or 4 of the OSI model and are difficult to mitigate without deep packet inspection or specialized hardware.

Examples:

• SYN flood: Exploits the TCP handshake process by sending a barrage of SYN packets to initiate connections but never completes them. The server allocates resources for each incomplete connection, eventually overwhelming its capacity to handle new ones.
• Ping of death: Sends ICMP packets that exceed the maximum allowable size for a single packet. When the target tries to reassemble these oversized packets, it may crash or behave unpredictably due to buffer overflows.
• Smurf attack: Uses ICMP Echo Requests sent to a network's broadcast address with the victim's IP spoofed as the source. This causes all devices in the network to send replies to the victim, flooding it with traffic.

Application-layer attacks target the application directly, rather than the infrastructure. These attacks are more sophisticated and harder to detect, as they often resemble normal user behavior. They aim to exhaust resources such as CPU, memory, or application-specific limits like database connections.

Examples:

• HTTP flood: Mimics legitimate web browsing by sending HTTP GET or POST requests. High volumes of such requests can slow down or crash the web server, especially if the requests trigger complex backend processing.
• Slowloris: Keeps many connections open to the target web server by sending partial HTTP requests slowly and never completing them. This exhausts the server's pool of concurrent connections and prevents legitimate users from connecting.
• DNS query flood: Sends a flood of seemingly valid DNS queries to the target DNS server. The server must process each query, leading to resource exhaustion and degradation or denial of DNS services.

4. Hybrid and Multi-Vector Attacks

Hybrid and multi-vector attacks blend multiple DDoS techniques—across volumetric, protocol, and application layers—within a single campaign. This fusion increases the attack’s resilience and adaptability, allowing it to bypass conventional security measures that are optimized for one type of threat.

For example, an attacker might initiate a volumetric flood using DNS amplification to saturate network links, then switch to a SYN flood to exhaust server connection tables, and finally deploy HTTP floods to crash web applications. The goal is to exploit weaknesses across multiple layers simultaneously or sequentially, confusing mitigation tools and delaying response.

These attacks are often automated using sophisticated botnets capable of adjusting tactics in real time based on the target’s defenses. Defending against them requires comprehensive DDoS protection that includes traffic analysis, behavior-based filtering, and adaptive rate limiting, often coordinated across multiple layers of the network stack.

5. Hit-and-Run Attacks

Hit-and-run attacks consist of repeated bursts of high-volume or high-impact traffic, each lasting only a few minutes. These short-lived attacks may seem benign in isolation but can cause cumulative disruption over time. They are particularly effective against organizations with slow or manual mitigation processes.

Because the attack periods are brief, traditional monitoring tools may not detect them in time to respond. After the traffic subsides, systems may revert to a vulnerable state, enabling repeated exploitation. Attackers use this technique to test defenses, cause repeated minor outages, or distract incident response teams from other concurrent threats.

Mitigating hit-and-run attacks involves setting up persistent monitoring and rate-limiting policies that remain active beyond the duration of individual attacks. Automated detection systems that can respond within seconds are crucial for limiting the damage.

6. Reflection and Amplification Attacks

Reflection and amplification attacks rely on misconfigured or unsecured third-party servers to deliver large volumes of traffic to a target. The attacker sends a small request to a server using the spoofed IP address of the victim. The server, thinking the request is legitimate, sends the much larger reply to the victim instead.

Popular protocols for this include DNS (domain name system), NTP (network time protocol), SSDP (simple service discovery protocol), and Memcached. For example, a 60-byte DNS query can result in a 4,000-byte response, yielding an amplification factor of over 60x.

These attacks are hard to block at the network edge because the malicious traffic appears to come from trusted sources. Effective countermeasures include ingress and egress filtering (to prevent IP spoofing), deploying rate limits on susceptible services, and using upstream providers or scrubbing centers that can filter out spoofed traffic.

7. DDoS Extortion (Ransom DDoS)

Ransom DDoS, or RDDoS, attacks do not always begin with actual traffic; they often start with a threatening message demanding payment to avoid or stop a DDoS attack. In many cases, attackers will launch a short proof-of-attack to demonstrate their capability, followed by a demand for cryptocurrency payment.

These campaigns may impersonate known hacker groups to add credibility and psychological pressure. Some attackers never follow through with an actual attack, relying entirely on the threat to coerce payment. Others escalate quickly if demands are not met, targeting critical business hours or high-profile digital services.

Organizations targeted by RDDoS should never pay the ransom, as this funds further criminal activity and provides no guarantee of relief. Instead, they should implement a proactive DDoS defense strategy, notify law enforcement, and work with their internet service provider or DDoS mitigation partner to absorb or reroute attack traffic.

Rate Limiting

Rate limiting is a preventive control that restricts the number of requests a client can make to a server over a specified time window. It is commonly applied per IP address, user account, or API key, and is used to mitigate abuse patterns such as brute-force login attempts, API scraping, or web request floods.

In the context of DDoS, rate limiting helps throttle suspicious traffic before it reaches application resources. It is particularly effective against application-layer attacks that rely on mimicking legitimate behavior at scale. For example, an HTTP flood may be stopped by limiting each IP to a reasonable number of requests per second.

Rate limiting can be implemented at various layers, including application servers, reverse proxies (like NGINX), cloud platforms, or at the edge using CDNs. It often uses token bucket or leaky bucket algorithms to track and enforce quotas. However, care must be taken to avoid affecting legitimate high-volume users, such as API clients or large customer networks, requiring smart rules and whitelisting capabilities.

Web Application Firewalls (WAFs)

A WAF sits between the user and a web application, analyzing incoming HTTP/S traffic and filtering out malicious requests. It provides rule-based protection against known attack signatures and behavioral anomalies, such as injection attempts, protocol violations, or unusual request rates.

Against DDoS attacks, WAFs are particularly effective at handling application-layer threats that target specific endpoints with complex requests. For instance, a WAF can block or challenge requests that resemble bot behavior or target expensive operations like database lookups or search queries.

Modern WAFs support dynamic rule updates, machine learning-based detection, and integration with threat intelligence feeds. They also offer rate-based rules, CAPTCHA challenges, geo-blocking, and IP reputation scoring. WAFs are typically deployed as part of a layered defense strategy and are most effective when tuned to the application’s traffic patterns and behaviors.

Anycast Network Diffusion

Anycast allows multiple servers in different geographic locations to advertise the same IP address. Routers direct client traffic to the nearest node based on routing protocol metrics, distributing load and enhancing fault tolerance.

For DDoS mitigation, Anycast’s distributed nature is a significant advantage. During an attack, malicious traffic is automatically spread across many data centers or edge locations, reducing the chance that any single site will be overwhelmed. This diffusion buys time for detection and response mechanisms to activate without immediate service degradation.

Anycast is commonly used in global content delivery networks (CDNs), DNS services, and cloud-based DDoS mitigation platforms. When paired with automatic traffic scrubbing and filtering, it forms a powerful first line of defense. However, building and maintaining an effective Anycast network requires substantial infrastructure and routing expertise.

Traffic Analysis and Anomaly Detection

This approach involves continuous monitoring of network and application traffic to identify patterns that deviate from established baselines. Detection can be statistical, using thresholds and heuristics, or powered by machine learning models trained on historical data.

In DDoS defense, anomaly detection enables early warning and rapid classification of threats. It can identify both high-volume volumetric attacks and subtle, low-rate application-layer attacks. For example, a spike in requests to a rarely used endpoint or a surge in incomplete TCP handshakes can indicate an attack in progress.

Effective traffic analysis tools visualize trends, generate real-time alerts, and integrate with automated mitigation workflows. Key metrics include request rate, source distribution, protocol mix, and response codes. To minimize false positives, systems must differentiate between legitimate traffic surges (e.g., flash crowds) and attack patterns, often using contextual awareness and adaptive baselining.