A network-layer attack targets the systems that move packets across a network, rather than the application running on top of it. It often takes the form of a high-volume flood that overwhelms bandwidth, routers, firewalls, load balancers, or other packet-handling infrastructure. In practice, this is the transport path that must stay available before a website, API, or service can even begin to respond.
This matters because availability can fail long before an application is technically compromised. Defenders may see congestion, dropped packets, or exhausted mitigation capacity instead of a traditional login or code-execution problem. Real-world defenses against this kind of attack rely on upstream filtering, rate limiting, traffic scrubbing, distributed capacity, and tested failover plans. When these controls are weak or untested, a network-layer flood can make essential services unreachable even if the servers themselves remain healthy.