distributed denial of service ddos definition

What Is a Distributed Denial-of-Service (DDoS) Attack?

A Distributed Denial-of-Service (DDoS) attack involves overwhelming a service with massive, distributed traffic, effectively “crashing” it so that legitimate users cannot access it. Imagine thousands of cars flooding a single highway—not because the cars are broken, but because the road is gridlocked.

This flood of traffic typically originates from a “botnet”—a large collection of computers or IoT devices infected with malware and remotely controlled to launch coordinated requests. Targets can include exchange websites, market data/trading APIs, blockchain RPC nodes, and even validator peer-to-peer (P2P) connections.

How Does a DDoS Attack Differ from a DoS Attack?

The key difference is scale and distribution: a DDoS attack is launched from multiple sources simultaneously, while a standard Denial-of-Service (DoS) attack typically comes from a single origin. DDoS attacks are much harder to block and trace because the malicious traffic is dispersed globally, akin to countless faucets turned on at once.

For defenders, a DoS attack can sometimes be mitigated by blocking a single IP address. In contrast, countering a DDoS attack requires upstream filtering and traffic diversion near network entry points, combined with application-level rate limiting and graceful degradation strategies.

How Does a DDoS Attack Work?

DDoS attacks generally fall into two main categories:

• Network Layer Floods: These attacks saturate bandwidth and connection resources with massive packets. Examples include SYN floods or UDP floods, which involve huge volumes of packets without executing business logic. There’s also “reflection amplification,” where attackers spoof the victim’s IP address and query multiple open services (like DNS or NTP). These services then send amplified response traffic to the victim—similar to borrowing loudspeakers to shout at the target.

• Application Layer Exhaustion: These mimic legitimate users making complex requests to drain CPU or database connections. Typical examples are HTTP floods or WebSocket abuse. In Web3 scenarios, endpoints for market data subscriptions or order placements are often prime targets. When attack traffic closely mimics real user behavior, it can bypass network-level filtering and directly consume application threads, cache, and database connection pools.

DDoS Attack Targets in Web3 Scenarios

In Web3, DDoS attacks often focus on key entry points such as exchange websites and trading/market data APIs, blockchain RPC nodes, full node P2P ports, cross-chain bridges, and block explorers.

For example, on an exchange like Gate, DDoS attacks on spot and derivatives APIs can cause slow page loads, interruptions in candlestick and order book feeds, order placement/cancellation timeouts, and stricter rate limits with more frequent error codes for API users. At the RPC layer, attacks on public nodes can result in timeouts for block/account queries, failed wallet balance refreshes, and slower smart contract calls.

For validator nodes, excessive P2P connection probes can disrupt block propagation and compromise block production and synchronization stability. If cross-chain bridges expose public interfaces, off-chain signing or proof services may become inaccessible under attack.

How to Identify DDoS Attack Symptoms and Log Indicators

A telltale sign is “sudden performance degradation without corresponding business metrics”: spikes in latency, increased timeouts and 5xx errors, and surges in traffic volume without matching conversions or transaction growth.

On the network side, you may see abnormal bandwidth usage at entry points, SYN queue saturation, and sudden geographic diversification of source IPs. On the application side, look for uneven QPS (queries per second), increased p95 latency, exhausted database connection pools, decreased cache hit rates, and sudden spikes in WebSocket sessions.

Log signatures include: repetitive or malformed User-Agent strings, surges in requests without Referrer headers, single IPs hitting many different URLs in a short period, or direct targeting of dynamic endpoints instead of static resources. For node and RPC services, typical patterns include homogeneous contract calls or high-frequency low-value queries.

Emergency Response to DDoS Attacks

1. Trigger Upstream Filtering and Rate Limiting: If necessary, temporarily “blackhole” the most targeted destination IPs or reroute them through scrubbing centers to protect core databases and matching engines from being overwhelmed.

2. Enable Business Degradation and Read-Only Modes: Exchanges should prioritize matching engines and asset security while reducing non-critical functions—for example, lazy loading charts, pausing unnecessary batch APIs, or shortening candlestick history windows.

3. Switch Quickly to Anycast or Backup Domains: Anycast deploys the same IP in multiple locations worldwide, letting users connect to the nearest node and naturally distributing traffic. Backup domains help isolate heavily targeted entry points.

4. Strengthen Application Layer Challenges and Authentication: Add CAPTCHAs to anonymous endpoints; implement more granular token bucket rate limits and peak controls on API keys; enforce signature checks or pre-warmed caches for high-cost requests.

5. Coordinate with ISPs and Security Vendors: Dynamically adjust filtering thresholds and patterns while maintaining observability—ensure key metrics, logs, and alerts remain effective.

6. Publish Status Updates and Risk Alerts for Users: For example, Gate’s status page can communicate impact scope and estimated recovery times. Advise users to set price protection and risk parameters when placing orders to avoid mistakes during network instability.

Long-Term DDoS Defense Strategy and Cost Considerations

Long-term defense requires an integrated approach—combining “traffic diversion, absorption, filtering, degradation.” At the network level, deploy high-bandwidth redundancy and traffic scrubbing at entry points. Combine Anycast with Content Delivery Networks (CDNs) to absorb traffic surges close to users; shut down unnecessary reflection ports or implement access controls on amplifiable services.

On the application side, implement multi-tier caching and read-write separation; staticize or precompute hotspot endpoints; use web application firewalls (WAF) to detect anomalous behavior; apply token bucket rate limiting for APIs with per-user QPS tiers and burst controls; provide private gateways, whitelisting, and source-based quotas for RPC endpoints.

From an engineering and organizational perspective: establish drills and response playbooks that clarify who triggers which controls under what circumstances; focus monitoring on critical SLOs (Service Level Objectives) like availability, p95 latency, and error rates; evaluate the marginal benefits of bandwidth reserves, scrubbing services, and compute redundancy according to business peaks and risk exposure.

Key Takeaways & Security Tips for DDoS Attacks

DDoS attacks do not directly steal assets but destabilize trading and queries—amplifying slippage, causing operational errors and increasing latency risks. For builders, it’s crucial to design layered defenses ahead of time and establish streamlined emergency procedures spanning both network and application layers. For users: if you experience abnormal access issues, consult official status pages, interact only through trusted portals like Gate, use limit/risk parameters when trading, and avoid large or highly leveraged trades during service disruptions. Industry reports indicate that both high-volume and application-layer DDoS attacks are still rising as of 2024—with peak volumes reaching Tbps levels (sources: Cloudflare, Akamai annual & quarterly reports). Proactive preparation and drills are almost always more cost-effective than post-incident recovery.

FAQ

Why is it called 'Distributed' Denial-of-Service? Can’t a Single Computer Launch an Attack?

The term “distributed” refers to attacks originating from thousands of compromised devices rather than just one. A single computer’s traffic is limited and easy for firewalls to block. But when malicious traffic is distributed globally across many machines, defenders cannot simply block one IP address. This distributed nature significantly increases both attack success rates and stealth.

What Happens if My Wallet or Account Is Targeted by a DDoS Attack?

While a wallet or account itself isn’t usually compromised by DDoS attacks (meaning funds aren’t stolen directly), exchanges or wallet platforms can go offline—preventing you from trading or withdrawing assets. Severe network delays during an attack may cause slippage or failed transactions. In some cases, attackers may exploit this window for further malicious activity. It’s recommended to use well-protected platforms (like Gate) with two-factor authentication enabled.

How Long Do DDoS Attacks Usually Last? When Will Service Be Restored?

The duration of a DDoS attack can range from minutes to hours or even days—depending on the attackers’ objectives and defenders’ response capabilities. Medium-scale attacks are typically mitigated within 30 minutes to 2 hours; large-scale attacks may take several hours for full recovery. Professional CDN protection and incident response teams can significantly reduce downtime.

Why Do Hackers Launch DDoS Attacks? What Are Their Motives?

Hackers have various motives for launching DDoS attacks—including extortion (demanding ransom payments), sabotage by competitors, political agendas, or even personal amusement. In the crypto sector, attackers may aim to prevent an exchange or project from going live or exploit downtime for other criminal activities. Understanding these motives helps organizations tailor their defense strategies more effectively.

What Can Regular Users Do to Protect Themselves from DDoS Impact?

While DDoS attacks primarily target platforms rather than individuals, you can take precautions: choose exchanges with robust protection infrastructure (like Gate), avoid making large trades during outages or instability, enable multi-factor authentication, regularly monitor accounts for suspicious activity—and diversify your assets across platforms to reduce overall risk exposure.