Network security and system performance evaluation stress testing is the key to ensuring service reliability and stability. Traditional stress testing is mainly used to evaluate the system under high load, while online DDoS stress testing specifically simulates distributed denial of service (DDoS) attacks to verify the system's anti-attack capabilities. Although both involve applying pressure to the target system, there are obvious differences in their test purposes, implementation methods, technical means and applicable scenarios. This article will describe the specific differences between multiple online DDoS stress tests and traditional stress tests.
　　1. Test Purpose and Security Differences
　　The core goal of traditional stress testing is to evaluate the performance of the system under normal or extreme business loads,
　　Server throughput: the maximum number of requests that the system can handle per unit time (such as QPS, TPS).
　　Resource consumption: the use of hardware resources such as CPU, memory, disk I/O, network bandwidth, etc. under high load.
　　Stability: whether the system will crash, memory leak, or surge in response delays under long-term high-concurrency requests.
　　This type of test is usually the robustness of business logic, such as whether it can withstand millions of users placing orders at the same time during large-scale events, or whether the video platform can support low-latency playback of tens of millions of live viewers.
　　The main purpose of online DDoS stress testing is to evaluate the defense capability of the target system under the impact of malicious traffic:
　　Network layer stress resistance: whether it can resist traffic attacks such as UDP Flood, ICMP Flood, SYN Flood, etc.
　　Application layer protection capability: whether it can identify and intercept HTTP Flood, Slowloris, CC attacks and other attacks that simulate real user behavior.
　　Effectiveness of security equipment: whether security measures such as firewalls, WAF (Web Application Firewall), CDN, cloud cleaning services, etc. can correctly filter malicious traffic. DDoS tests the reliability of the security defense system, rather than the optimization of business logic.
　　II. Test traffic method
　　Traditional stress testing usually uses legitimate and structured business requests.
　　HTTP/HTTPS request: simulates user behaviors such as visiting web pages, submitting forms, and API calls.
　　Database query: test SQL query performance, such as indexing efficiency under high concurrency.
　　Message pressure: evaluate the performance of middleware such as Kafka and RabbitMQ under high throughput.
　　Common tools include JMeter, LoadRunner, Locust, etc., which can simulate the access patterns of tens of thousands or even millions of "normal users" and generate detailed performance reports.
　　Online DDoS stress testing uses malicious traffic simulation.
　　Network layer attacks: such as UDP Flood (using connectionless protocols to exhaust bandwidth), ICMP Flood (Ping flooding attack), SYN Flood (half-connection attack to exhaust TCP connection pool).
　　Application layer attacks: such as HTTP Flood (simulating a large number of legitimate requests to exhaust server resources), Slowloris (maintaining a large number of slow HTTP connections to occupy server threads), DNS amplification attacks (using DNS protocol defects to create large traffic).
　　Hybrid attacks: using multiple attack methods at the same time to bypass a single protection mechanism.
　　DDoS testing usually relies on professional tools, such as LOIC (low orbit ion cannon), HOIC (advanced version of LOIC), Mirai botnet simulator, etc. Some companies even rent real DDoS testing platforms (such as Cloudflare's Attack Simulation or BreakingPoint).

　　3. Test environment
　　Traditional stress testing is usually conducted in a controlled environment:
　　Pre-production environment: Before the official launch, use a server with the same configuration as the production environment for testing.
　　Shadow traffic: Copy real user requests to the test environment without affecting online business.
　　Progressive stress: Gradually increase the load from low concurrency to observe the turning point of system performance (such as a sharp increase in response time or an increase in error rate).
　　The test team can accurately control parameters such as request frequency, number of concurrent users, test duration, and stop the test at any time to avoid system crashes.
　　Online DDoS stress testing often needs to be conducted in a real production environment:
　　The real performance of security equipment: Only in a real network environment can the effectiveness of firewalls and traffic cleaning devices be verified.
　　The protection capabilities of ISPs and cloud service providers: Many companies rely on operators or cloud vendors to mitigate attacks, and these protection mechanisms can only take effect under real traffic.
　　Unpredictability of attack traffic: Real DDoS attacks may come from botnets around the world, and testing needs to simulate this distributed feature.
　　DDoS testing usually requires:
　　Advance notification: avoid triggering the emergency response mechanism of the security team.
　　Time-limited testing: avoid long-term impact on normal business.
　　Traffic monitoring: real-time observation of network bandwidth, server load, and interception of security devices.
　　IV. Test results
　　The output of traditional stress testing usually includes:
　　Performance indicators: such as average response time, error rate, and throughput.
　　Resource usage: CPU, memory, disk I/O, database query efficiency.
　　Bottleneck analysis: find out the key points of system performance degradation (such as missing database indexes, cache invalidation, etc.).
　　The results of DDoS testing pay more attention to:
　　The interception rate of protective equipment: how much malicious traffic is successfully cleaned or discarded.
　　Business availability: whether the core service is still accessible during the attack.
　　Recovery time: the time required for the system to return to normal after the attack stops (such as whether automatic elastic expansion is effective).
　　Traditional stress testing is an important means of performance optimization, helping developers find system bottlenecks and improve user experience. Online DDoS stress testing is a key link in security protection, ensuring that enterprises can still maintain service stability under real attacks. The two are not contradictory, but complementary. Modern enterprises should combine performance testing + security attack and defense drills to build a more robust infrastructure.