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Default Gateway

The network device, usually a router, that a host sends traffic to when the destination is outside its own local network. It is the exit point from a subnet to the wider network and internet.

When a host needs to reach an address not on its local subnet, it forwards the packet to its default gateway, which routes it onward. Understanding the default gateway helps defenders trace how traffic leaves a network, reason about routing and segmentation, and recognize where egress controls and monitoring should sit. A compromised or spoofed gateway is also a man-in-the-middle risk on local networks.

Introduced in: Networking Foundations

Examples

  • A workstation sending internet-bound traffic to its default gateway router.
  • Tracing how a subnet's traffic exits through its gateway during analysis.
  • Placing egress filtering at the gateway between a subnet and the internet.