How to Handle a DDoS Attack: Prevention and Response
A Distributed Denial of Service attack floods your server with overwhelming traffic from many sources simultaneously, aiming to make your site unavailable to legitimate visitors. Whether it's targeted at your business specifically or just opportunistic, being prepared — both to prevent it and to respond quickly if it happens — makes an enormous difference in how much damage it actually causes.
Understanding the Different Types of DDoS Attacks
Volumetric attacks simply overwhelm your available bandwidth with sheer traffic volume, exhausting your network capacity before requests even reach your application layer.
Protocol attacks exploit weaknesses in network protocols (like SYN floods that exhaust connection-handling resources) to exhaust server or network infrastructure resources rather than bandwidth specifically.
Application layer attacks target your actual application with seemingly legitimate-looking requests (like repeated searches or login attempts) designed to exhaust application-level resources — these are often harder to distinguish from genuine traffic spikes.
Prevention: Use a CDN or DDoS Mitigation Service
The single most effective prevention measure most sites can implement is routing traffic through a CDN or dedicated DDoS mitigation service before it reaches your origin server. These services have massive infrastructure specifically designed to absorb and filter attack traffic at scale — far beyond what most individual sites could handle on their own origin infrastructure, and many include this protection as a standard feature rather than a costly add-on.
Prevention: Rate Limiting
Implementing rate limiting on your application (particularly on expensive endpoints like search, login, or API calls) prevents any single source from making an excessive number of requests in a short period, which helps against both genuine DDoS attempts and less coordinated abuse or scraping.
Prevention: Web Application Firewall (WAF)
A WAF can identify and block malicious traffic patterns before they reach your application, filtering out known attack signatures and suspicious request patterns that legitimate traffic wouldn't exhibit. Many CDN and hosting providers include WAF functionality as part of their service.
Prevention: Monitor for Early Warning Signs
Continuous monitoring that alerts you to unusual traffic spikes, abnormal request patterns, or degraded response times gives you the earliest possible warning that an attack may be starting — often before it escalates to a full outage, giving you time to respond proactively rather than reactively.
During an Attack: Stay Calm and Assess
If you suspect you're under attack, first confirm it genuinely is malicious traffic rather than a legitimate (if unexpected) traffic spike — a successful marketing campaign or viral social media mention can produce traffic patterns that superficially resemble an attack. Check your traffic logs for the actual pattern: is it coming from an unusually concentrated set of IP ranges, hitting unusual endpoints, or showing bot-like request patterns (identical timing, unusual user agents)?
During an Attack: Activate Mitigation
If you have a CDN or DDoS mitigation service already in place, most offer an "under attack" mode that applies more aggressive filtering (like requiring JavaScript challenges or CAPTCHAs before allowing access) temporarily, at the cost of some added friction for legitimate visitors, in exchange for much stronger attack mitigation during the active incident.
During an Attack: Communicate With Your Hosting Provider
If the attack is severe enough that your own mitigation measures aren't sufficient, contact your hosting provider immediately — many have their own network-level mitigation capabilities and experience handling these situations, and early communication gives them time to help before the situation worsens further.
After an Attack: Review and Strengthen
Once the immediate incident is resolved, review what happened: How was the attack detected? How long until mitigation was effective? What worked well, and what gaps became apparent? Use this to strengthen your defenses and response process for next time — DDoS attacks, once a site has been targeted, sometimes recur, so treating the first incident as a one-off rather than using it to improve preparedness is a missed opportunity.
Have an Incident Communication Plan
If the attack causes visible downtime, having a plan for communicating with affected users or customers (a status page, a prepared social media response) reduces the reputational damage compared to visitors simply encountering an unexplained outage with no acknowledgment.
The Bottom Line
DDoS attacks are largely a preventable-impact problem rather than a preventable-occurrence problem — you generally can't stop someone from attempting an attack, but proper mitigation infrastructure (CDN protection, rate limiting, a WAF) can mean the difference between a brief blip that most visitors never notice and a prolonged, damaging outage.