When a DDoS attack hits, the first few minutes determine whether it becomes a minor incident or a major outage. The good news is that DDoS campaigns usually leave fingerprints: sudden spikes, unusual traffic patterns, overloaded resources, and user-facing errors. The bad news is that it is easy to dismiss early signs as “normal traffic” until customers start complaining.
This guide shows you the clearest signs of a distributed denial of service attack, how to confirm what you are seeing, and the best way to respond.
Key takeaways
- DDoS attacks often start small, then ramp up quickly.
- Monitoring, alerts, and runbooks matter more than improvisation.
- Attackers sometimes pair DDoS with other tactics, like phishing or credential attacks.
- Speed of response is your strongest advantage.
What counts as a DDoS attack?
A DDoS attack (distributed denial of service attack) uses many devices or sources to overwhelm a service with traffic. The goal is to reduce performance or make the system unavailable for genuine users.
Signs a DDoS attack may be starting
1. Sudden spikes in traffic
- Huge jumps in requests per second (RPS).
- Unexplained bandwidth consumption.
- Traffic levels that ignore normal business patterns.
2. Concentrated traffic from unusual sources
- Large volume from a small set of IP ranges.
- Unnatural geographic concentration.
- “Noisy” user agents or empty referrers.
3. Increased errors and timeouts
Common symptoms include:
- Slow page loads.
- HTTP 429 (too many requests).
- HTTP 503/504 (service unavailable/timeouts).
- Frequent disconnects from web sockets or APIs.
4. Infrastructure resource exhaustion
Even without a bandwidth spike, you might see:
- CPU load climbing rapidly.
- Memory pressure.
- Thread or connection pool exhaustion.
DDoS warning signs (quick lookup)
| Symptom | What it usually means |
|---|---|
| Traffic spike without marketing activity | DDoS likely |
| Errors climbing before traffic spike | Resource exhaustion |
| Traffic from unusual region/IP patterns | Botnet behaviour |
| Security alerts on multiple services | Coordinated attack |
How to confirm you are under a DDoS attack
Step 1: Check baseline vs current traffic
Compare the current traffic and request patterns against your normal baseline, including time of day, region, and device mix.
Step 2: Correlate logs and monitoring
Look for patterns across:
- Web server logs.
- WAF logs.
- CDN analytics.
- Load balancer metrics.
Step 3: Rule out normal causes
Before declaring an incident, confirm there is no legitimate cause such as:
- A promotional campaign.
- Viral social activity.
- Scheduled product launch.
Step 4: Activate your runbook
If the signs match and impact is escalating, treat it as an active incident.
Responding to a DDoS attack before it is too late
Immediate actions (first 15 minutes)
- Notify your hosting provider and mitigation vendor.
- Enable rate limiting and WAF rules.
- Switch to “essential services only” if possible.
- Increase logging and preserve evidence.
- Communicate incident status to stakeholders.
Stabilisation phase (first hour)
- Identify the attack type (volumetric, protocol, application layer).
- Tune filters and rules to reduce collateral damage.
- Monitor for secondary attacks, such as phishing campaigns.
This is where phishing simulations and ongoing training help. If staff can recognise suspicious activity, they respond faster when attackers combine tactics.
Prevention and resilience planning
DDoS resilience is a process, not a one-time setup.
Build a layered defence
- DDoS protection provider or CDN.
- WAF rules tailored to your application.
- Rate limiting on APIs and login endpoints.
- Monitoring with alert thresholds based on baselines.
Train your team
Technology is only half the solution, with cyber security awareness training, staff are more confident reporting anomalies and escalating incidents quickly.
Book a demo to see how our awareness training and phishing simulations support DDoS resilience.
