All DDoS Definitions
DDoS Definition

Cache-Busting Attack

A cache-busting attack is a Layer 7 (application) attack vector, one of the attack classes a thorough DDoS test is built to exercise. Normally a CDN absorbs repeat requests by serving them from its edge cache, shielding the origin. A cache-busting attack defeats that by appending a unique, random query string (for example ?x=8f3a1c) to every request, so each URL looks brand new to the cache. Because no two requests match a cached object, the edge records a cache miss on all of them and forwards each one to the origin. The attacker effectively turns the CDN into a pass-through, concentrating the full request rate on the origin server and its backend rather than letting it be absorbed at the edge.

Cache-busting: unique URL every time, always a miss Attacker GET /p?x=8f3a1c GET /p?x=b7c209 GET /p?x=41de6a unique query string on every request CDN edge cache normal traffic: HIT served from edge, origin idle every busted URL: MISS no cached object matches, forward to origin 100% forwarded Origin server CDN becomes a pass-through full request rate lands here CPU + backend DB saturated Test drives cache-hit ratio toward zero to measure real origin exposure, and checks whether edge rules normalize query strings or rate-limit misses. BlackNeuron™
Cache-busting attack: each request carries a unique random query string, so every one is a CDN cache miss and gets forwarded to the origin instead of served from the edge

Why it matters in DDoS testing

Cache-busting matters because a CDN's headline absorption figure assumes a healthy cache-hit ratio, and this traffic drives that ratio toward zero. A DDoS test measures the origin's real exposure by generating cache-busting requests and watching origin request rate, cache-hit ratio, and whether edge rules (normalizing or stripping unknown query parameters, or rate-limiting cache misses) actually hold the line. For how edge caching and origin protection interact across providers, see AWS Shield versus Cloudflare.