All DDoS Definitions
DDoS Testing Definition

Anycast

Anycast is a network addressing method in which the same IP address is announced from many locations at once, and the routing layer delivers each user's traffic to the nearest announcing node. DDoS mitigation providers rely on anycast to spread incoming attack traffic across many regional points of presence rather than concentrating it on a single origin.

Anycast: one IP announced from many edges, flood divided Attack + user traffic all to one IP same IP 203.0.113.9 announced from every PoP PoP US-East holds its share of the load PoP EU-West holds its share of the load PoP APAC holds its share of the load Origin fronted by the edge bypass: origin reachable by raw IP defeats anycast entirely A test validates two things: how much aggregate volume the edge absorbs, and whether every path is actually fronted. BlackNeuron™
Diagram of anycast: one IP announced from many points of presence dividing an attacker's flood across the edge, with a dashed bypass path showing a raw-IP-reachable origin defeating the edge entirely

Why it matters in DDoS testing

Anycast is the structural reason large volumetric attacks can be absorbed at all: the load is divided across the edge network instead of landing on one link. A DDoS test validates two things about an anycast deployment. First, absorption: how much aggregate volume the distributed edge holds before clean traffic degrades. Second, and more commonly a finding, coverage: whether the anycast edge actually fronts every reachable path to the origin, or whether the origin is independently reachable by IP and therefore bypassable.

For how edge absorption fits the broader methodology, see The Complete Guide to DDoS Testing.